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https://leetcode.com/problems/longest-palindromic-substring/discuss/2288241/simple-python-dp
class Solution: def longestPalindrome(self, s): longest_palindrome = '' dp = [[0] * len(s) for _ in range(len(s))] for i in range(len(s)): dp[i][i] = True longest_palindrome = s[i] for i in range(len(s) - 1, -1, -1): for j in range(i + 1, len(s)): print("i: %d, j: %d" % (i,j)) if s[i] == s[j]: # if the chars mathces if j - i == 1 or dp[i + 1][j - 1] is True: dp[i][j] = True if len(longest_palindrome) < len(s[i:j + 1]): longest_palindrome = s[i:j + 1] return longest_palindrome
longest-palindromic-substring
simple python dp
gasohel336
1
448
longest palindromic substring
5
0.324
Medium
200
https://leetcode.com/problems/longest-palindromic-substring/discuss/2251262/python3-oror-easy-oror-solution
class Solution: def longestPalindrome(self, s: str) -> str: res="" resLen=0 finalLeftIndex=0 finalRightIndex=0 for i in range(len(s)): #for odd length of palindromes l,r=i,i while l>=0 and r<len(s) and s[l]==s[r]: if (r-l+1)>resLen: # res=s[l:r+1] finalLeftIndex=l finalRightIndex=r+1 resLen=r-l+1 l-=1 r+=1 #for even length of palindromes l,r=i,i+1 while l>=0 and r<len(s) and s[l]==s[r]: if (r-l+1)>resLen: # res=s[l:r+1] finalLeftIndex=l finalRightIndex=r+1 resLen=r-l+1 l-=1 r+=1 return s[finalLeftIndex:finalRightIndex]
longest-palindromic-substring
python3 || easy || solution
_soninirav
1
231
longest palindromic substring
5
0.324
Medium
201
https://leetcode.com/problems/longest-palindromic-substring/discuss/2156912/Python3-or-Very-Easy-to-Understand-or-simple-approach
class Solution: def longestPalindrome(self, s: str) -> str: res = '' n = len(s) mxlen = 0 for i in range(n): for j in range(max(i+1, i+mxlen), n+1): if s[i]==s[j-1]: sub = s[i: j] if sub == sub[::-1] and len(sub)>len(res): res=sub mxlen = len(res) return res
longest-palindromic-substring
Python3 | Very Easy to Understand | simple approach
H-R-S
1
62
longest palindromic substring
5
0.324
Medium
202
https://leetcode.com/problems/longest-palindromic-substring/discuss/1861817/Simple-Python-Solution-oror-85-Faster-oror-Memory-less-than-99
class Solution: def longestPalindrome(self, s: str) -> str: def get_palindrome(s,l,r): while l>=0 and r<len(s) and s[l]==s[r]: l-=1 ; r+=1 return s[l+1:r] ans='' for i in range(len(s)): ans1=get_palindrome(s,i,i) ; ans2=get_palindrome(s,i,i+1) ans=max([ans,ans1,ans2], key=lambda x:len(x)) return ans
longest-palindromic-substring
Simple Python Solution || 85% Faster || Memory less than 99%
Taha-C
1
348
longest palindromic substring
5
0.324
Medium
203
https://leetcode.com/problems/longest-palindromic-substring/discuss/1761378/Python-3-Expand-from-center
class Solution: def longestPalindrome(self, s: str) -> str: longest = 0 sub = '' def expand(left, right): nonlocal longest, sub while left >= 0 and right < len(s) and s[left] == s[right]: length = right-left+1 if length > longest: longest = length sub = s[left:right+1] left -= 1 right += 1 for i in range(len(s)): expand(i, i) expand(i, i+1) return sub
longest-palindromic-substring
[Python 3] Expand from center
leet4ever
1
230
longest palindromic substring
5
0.324
Medium
204
https://leetcode.com/problems/longest-palindromic-substring/discuss/1471768/PyPy3-Simple-solution-w-comments
class Solution: def longestPalindrome(self, s: str) -> str: # Check if a string is palindrome # within the given index i to j def isPal(s,i,j): while i < j: if s[i] != s[j]: break i += 1 j -= 1 else: return True return False # Init p = (0,0) # Portion of the string to be checked as palindrome n = len(s) # Base Case if n == 1: return s # Base Case if isPal(s,0,n-1): return s # For all other case for j in range(n): # Start from the begining i = 0 # While current index i is less than # end index j while i < j: # Check for palindrome only if # first and last character of a portion # of the string is similar if s[i] == s[j]: # Check if size of the current portion is # greater then the last max palindrome string. # Then check if this portion is palindrome. # Update the portion with current indexes if (p[1] - p[0]) < (j-i) and isPal(s,i,j): p = (i,j) i += 1 # Return the longest protion of the string found to be palindrome return s[p[0]:p[1]+1]
longest-palindromic-substring
[Py/Py3] Simple solution w/ comments
ssshukla26
1
665
longest palindromic substring
5
0.324
Medium
205
https://leetcode.com/problems/longest-palindromic-substring/discuss/756544/Simple-Python-code-oror-Faster-than-70.29-of-Python3
class Solution: def longestPalindrome(self, s: str) -> str: answer = "" for i in range(len(s)): odd = self.palindrome(s, i, i) even = self.palindrome(s, i, i+1) large = odd if len(odd) > len(even) else even answer = large if len(large) >= len(answer) else answer return answer def palindrome(self, s, left, right): IndexL = 0 IndexR = 0 while left >= 0 and right < len(s): if s[left] == s[right]: IndexL = left IndexR = right else: break left -= 1 right += 1 return s[IndexL: IndexR+1]
longest-palindromic-substring
Simple Python code || Faster than 70.29% of Python3
dharmakshii
1
439
longest palindromic substring
5
0.324
Medium
206
https://leetcode.com/problems/longest-palindromic-substring/discuss/249433/My-simple-and-easy-understanding-DP-Python-solution
class Solution: def longestPalindrome(self, s: str) -> str: length = len(s) dp = {} max_len = 1 start = 0 for _len in range(2, length + 1): i = 0 while i <= length - _len: j = i + _len - 1 if _len <= 3: dp[(i, j)] = s[i] == s[j] elif s[i] == s[j]: dp[(i, j)] = dp[(i + 1, j - 1)] else: dp[(i, j)] = False if dp[(i, j)] and _len > max_len: max_len = _len start = i i += 1 return s[start:start + max_len]
longest-palindromic-substring
My simple and easy understanding DP Python solution
mazheng
1
802
longest palindromic substring
5
0.324
Medium
207
https://leetcode.com/problems/longest-palindromic-substring/discuss/249433/My-simple-and-easy-understanding-DP-Python-solution
class Solution: def longestPalindrome(self, s: str) -> str: length = len(s) dp = {} max_len = 1 start = 0 for _len in range(2, length + 1): i = 0 while i <= length - _len: j = i + _len - 1 if _len <= 3 and s[i] == s[j]: dp[(i, j)] = True if _len > max_len: max_len = _len start = i elif s[i] == s[j] and dp.get((i + 1, j - 1)): dp[(i, j)] = True if _len > max_len: max_len = _len start = i i += 1 return s[start:start + max_len]
longest-palindromic-substring
My simple and easy understanding DP Python solution
mazheng
1
802
longest palindromic substring
5
0.324
Medium
208
https://leetcode.com/problems/longest-palindromic-substring/discuss/249433/My-simple-and-easy-understanding-DP-Python-solution
class Solution: def longestPalindrome(self, s: str) -> str: length = len(s) dp = {} max_len = 1 start = 0 for _len in range(2, length + 1): i = 0 while i <= length - _len: j = i + _len - 1 if (_len <= 3 and s[i] == s[j]) or (s[i] == s[j] and dp.get((i + 1, j - 1))): dp[(i, j)] = True if _len > max_len: max_len = _len start = i i += 1 return s[start:start + max_len]
longest-palindromic-substring
My simple and easy understanding DP Python solution
mazheng
1
802
longest palindromic substring
5
0.324
Medium
209
https://leetcode.com/problems/longest-palindromic-substring/discuss/2845651/Python
class Solution: def longestPalindrome(self, s: str) -> str: if not s: return '' def extend(s:str, i:int, j:int) -> Tuple[int, int]: while i>=0 and j < len(s): if s[i] != s[j]: break i -= 1 j += 1 return i+1, j-1 indices = [0,0] for i in range(len(s)): l1, r1 = extend(s, i, i) if r1-l1 > indices[1] - indices[0]: indices = l1, r1 if i+1 < len(s) and s[i]== s[i+1]: l2, r2 = extend(s, i, i+1) if r2-l2 > indices[1] - indices[0]: indices = l2, r2 return s[indices[0]:indices[1]+1]
longest-palindromic-substring
Python
Kishore1K
0
2
longest palindromic substring
5
0.324
Medium
210
https://leetcode.com/problems/longest-palindromic-substring/discuss/2840979/Manacher's-Algorithm-oror-Python-oror-Beats-98-oror-O(n)-time
class Solution: def longestPalindrome(self, text: str) -> str: N = len(text) if N == 0: return if N == 1: return text N = 2*N+1 # Position count L = [0] * N L[0] = 0 L[1] = 1 C = 1 # centerPosition R = 2 # centerRightPosition i = 0 # currentRightPosition iMirror = 0 # currentLeftPosition maxLPSLength = 0 maxLPSCenterPosition = 0 start = -1 end = -1 diff = -1 for i in range(2,N): # get currentLeftPosition iMirror for currentRightPosition i iMirror = 2*C-i L[i] = 0 diff = R - i # If currentRightPosition i is within centerRightPosition R if diff > 0: L[i] = min(L[iMirror], diff) # Attempt to expand palindrome centered at currentRightPosition i # Here for odd positions, we compare characters and # if match then increment LPS Length by ONE # If even position, we just increment LPS by ONE without # any character comparison try: while ((i + L[i]) < N and (i - L[i]) > 0) and \ (((i + L[i] + 1) % 2 == 0) or \ (text[(i + L[i] + 1) // 2] == text[(i - L[i] - 1) // 2])): L[i]+=1 except Exception as e: pass if L[i] > maxLPSLength: # Track maxLPSLength maxLPSLength = L[i] maxLPSCenterPosition = i # If palindrome centered at currentRightPosition i # expand beyond centerRightPosition R, # adjust centerPosition C based on expanded palindrome. if i + L[i] > R: C = i R = i + L[i] # Uncomment it to print LPS Length array # printf("%d ", L[i]); start = (maxLPSCenterPosition - maxLPSLength) // 2 end = start + maxLPSLength - 1 return text[start:end+1]
longest-palindromic-substring
Manacher’s Algorithm || Python || Beats 98% || O(n) time
joetrankang
0
5
longest palindromic substring
5
0.324
Medium
211
https://leetcode.com/problems/longest-palindromic-substring/discuss/2838180/Python-On2-solution-very-simple.
class Solution: def longestPalindrome(self, s: str) -> str: n = len(s) res = '' def find(i, j): nonlocal res while 0<=i<n and 0<=j<n: ss = s[i: j+1] if ss == ss[::-1]: if len(ss) > len(res): res = ss i -= 1 j += 1 else: break for i in range(n): find(i, i) find(i, i+1) return res
longest-palindromic-substring
Python On2 solution - very simple.
florinbasca
0
7
longest palindromic substring
5
0.324
Medium
212
https://leetcode.com/problems/longest-palindromic-substring/discuss/2827771/Python-(Simple-Maths)
class Solution: def is_palindrome(self,s,left,right): while left >= 0 and right < len(s) and s[left] == s[right]: left -= 1 right += 1 return s[left+1:right] def longestPalindrome(self, s): ans = [] for i in range(len(s)): ans.append(self.is_palindrome(s,i,i)) ans.append(self.is_palindrome(s,i,i+1)) return max(ans, key = len)
longest-palindromic-substring
Python (Simple Maths)
rnotappl
0
6
longest palindromic substring
5
0.324
Medium
213
https://leetcode.com/problems/longest-palindromic-substring/discuss/2825598/Python%3A-tracking-character-positions
class Solution: def longestPalindrome(self, s: str) -> str: positions = dict() palindrome = s[0] for j, char in enumerate(s): if char in positions: for i in positions[char]: if (j - i + 1) <= len(palindrome): break candidate = s[i : j+1] if candidate == candidate[::-1]: palindrome = candidate break positions[char].append(j) else: positions[char] = [j] return palindrome
longest-palindromic-substring
Python: tracking character positions
kwabenantim
0
6
longest palindromic substring
5
0.324
Medium
214
https://leetcode.com/problems/longest-palindromic-substring/discuss/2825598/Python%3A-tracking-character-positions
class Solution: def longestPalindrome(self, s: str) -> str: n = len(s) isPalindrome = [[False] * n for _ in range(n)] for i in range(n-1): isPalindrome[i][i] = True if s[i] == s[i+1]: isPalindrome[i+1][i] = True isPalindrome[n-1][n-1] = True iMax = jMax = 0 positions = dict() for j, char in enumerate(s): if char in positions: for i in positions[char]: if isPalindrome[i+1][j-1]: isPalindrome[i][j] = True if (j - i) > (jMax - iMax): iMax, jMax = i, j positions[char].append(j) else: positions[char] = [j] return s[iMax:jMax+1]
longest-palindromic-substring
Python: tracking character positions
kwabenantim
0
6
longest palindromic substring
5
0.324
Medium
215
https://leetcode.com/problems/longest-palindromic-substring/discuss/2823984/Manacher-Algorithm-faster-than-97-O(n)
class Solution: def longestPalindrome(self, s: str) -> str: # as you see we will use a string called t # t will be our old s string but delimited by ^# and #$ # Between each character of s there will be # t = "^#" + "#".join(s) + "#$" size_t = len(t) # p will contain for an index i the radius of the longest palindrome which can be find from this index # so from i - p[i] to i + p[i] we are facing a palindrome p = [0] * size_t d = c = 0 # c will be our center # and d the distance of the highest palindrome we can found at c index for i in range(1, size_t - 1): mirror = 2 * c - i # it is the index of the mirror of i by c. It is c - (i - c) # it can be resumed at 2 * c - i # given mirror the mirror of i by c, # if i + p[mirror] <= d we can initalize p[i] with the value of p[mirror] if i + p[mirror] <= d: p[i] = p[mirror] #we will make growth the palindrome while (t[i + 1 + p[i]] == t[i - 1 - p[i]]): p[i] += 1 #we will adjust the center if necessary if i + p[i] > d: d = i + p[i] c = i (k, i) = max((p[i], i) for i in range(1, size_t - 1)) # k is the size of the longest palindrome and i the index # the longuest palindrome start at (i - k) // 2 and finish at ((i + k) // 2 ) #so we return the string going from the start to the end return s[(i- k) // 2 : (i + k) // 2]
longest-palindromic-substring
Manacher Algorithm faster than 97% O(n)
diavollo
0
12
longest palindromic substring
5
0.324
Medium
216
https://leetcode.com/problems/longest-palindromic-substring/discuss/2819045/Python-Slow-Solution-Beginner
class Solution: def longestPalindrome(self, s: str) -> str: if s == s[::-1]: return s check = [] l = 0 while l != len(s): count = 0 for i in range(l,len(s)): sub = s[l:len(s)- count] if sub == sub[::-1]: check.append([len(sub), sub]) count +=1 l+=1 return max(check)[1]
longest-palindromic-substring
Python Slow Solution Beginner
Jashan6
0
2
longest palindromic substring
5
0.324
Medium
217
https://leetcode.com/problems/longest-palindromic-substring/discuss/2811057/Two-Pointer-Approach-oror-Python
class Solution: def longestPalindrome(self, s: str) -> str: res = '' length = 0 for i in range(len(s)): # checking for odd length left, right = i, i while left >= 0 and right < len(s) and s[left] == s[right]: if (right - left + 1) > length: res = s[left:right + 1] length = (right - left + 1) left -= 1 right += 1 # checking for odd length left, right = i, i + 1 while left >= 0 and right < len(s) and s[left] == s[right]: if (right - left + 1) > length: res = s[left:right + 1] length = (right - left + 1) left -= 1 right += 1 return res
longest-palindromic-substring
Two Pointer Approach || Python
darsigangothri0698
0
10
longest palindromic substring
5
0.324
Medium
218
https://leetcode.com/problems/longest-palindromic-substring/discuss/2808156/Counting-Ripples-in-a-Pond
class Solution: def longestPalindrome(self, s: str) -> str: start, extent = 0, 1 for i in range(len(s) - 1): possLen = 2 * min(i + 1, len(s) - i) if i >= len(s) // 2 and extent > possLen: break if possLen > extent: j, jEnd = 0, min(len(s) - i - 1, i + 1) while j < jEnd and s[i + j + 1] == s[i - j]: j += 1 if 2 * j > extent: start, extent = i - j + 1, 2 * j if possLen - 1 > extent: j, jEnd = 1, min(len(s) - i, i + 1) while j < jEnd and s[i + j] == s[i - j]: j += 1 if 2 * j - 1 > extent: start, extent = i - j + 1, 2 * j - 1 return s[start:start + extent]
longest-palindromic-substring
Counting Ripples in a Pond
constantstranger
0
5
longest palindromic substring
5
0.324
Medium
219
https://leetcode.com/problems/longest-palindromic-substring/discuss/2806129/Very-easy-python-solution-(ACCEPTED)
class Solution: def longestPalindrome(self, s: str) -> str: left = right = 0 palindrome = "" while left < len(s) and (len(s)-left) > len(palindrome): right = left while right < len(s): if s[left: right + 1] == s[left: right + 1][::-1]: if len(s[left: right + 1]) > len(palindrome): palindrome = s[left: right + 1] right += 1 left += 1 return palindrome
longest-palindromic-substring
Very easy python solution (ACCEPTED)
nehavari
0
23
longest palindromic substring
5
0.324
Medium
220
https://leetcode.com/problems/longest-palindromic-substring/discuss/2804789/hehe
class Solution: def longestPalindrome(self, s: str) -> str: pal = '' temp = '' f = 0 t = s[:-1] if s == s[::-1]: return s for i in range(len(s)): for j in range(f, len(s)+1): if s[i:j] == (s[i:j])[::-1] and len(s[i:j]) > f: pal = s[i:j] f = len(pal) return pal
longest-palindromic-substring
hehe
user0355Kw
0
3
longest palindromic substring
5
0.324
Medium
221
https://leetcode.com/problems/longest-palindromic-substring/discuss/2803633/Palindrome-substring-Python-Solution-Time-complexity-O(n*n)
class Solution: def longestPalindrome(self, s: str) -> str: res='' reslen=0 for i in range(len(s)): l,r=i,i while l>=0 and r<len(s) and s[l]==s[r]: if (r-l+1) > reslen: res=s[l:r+1] reslen=r-l+1 l-=1 r+=1 l,r=i,i+1 while l>=0 and r<len(s) and s[l]==s[r]: if (r-l+1) > reslen: res=s[l:r+1] reslen=r-l+1 l-=1 r+=1 return res
longest-palindromic-substring
Palindrome substring Python Solution Time complexity O(n*n)
Jai_Trivedi
0
6
longest palindromic substring
5
0.324
Medium
222
https://leetcode.com/problems/longest-palindromic-substring/discuss/2798602/Longest-Palindrome-using-python3
class Solution: def longestPalindrome(self, s: str) -> str: n=len(s) def expand_pallindrome(i,j): while 0<=i<=j<n and s[i]==s[j]: i-=1 j+=1 return (i+1, j) res=(0,0) for i in range(n): b1 = expand_pallindrome(i,i) b2 = expand_pallindrome(i,i+1) res=max(res, b1, b2,key=lambda x: x[1]-x[0]+1) # find max based on the length of the pallindrome strings. return s[res[0]:res[1]]
longest-palindromic-substring
Longest Palindrome using python3
user1885uW
0
6
longest palindromic substring
5
0.324
Medium
223
https://leetcode.com/problems/longest-palindromic-substring/discuss/2790471/dynammic-programming-O(n2)
class Solution: def longestPalindrome(self, s: str) -> str: dp = [[False]*len(s) for _ in range(len(s))] for i in range(len(s)): dp[i][i] = True ans=s[0] for j in range(len(s)): for i in range(j): if s[i]==s[j] and (dp[i+1][j-1] or j == i+1): dp[i][j]=True if j - i+1 > len(ans): ans = s[i:j+1] return ans
longest-palindromic-substring
dynammic programming O(n^2)
haniyeka
0
14
longest palindromic substring
5
0.324
Medium
224
https://leetcode.com/problems/longest-palindromic-substring/discuss/2790446/brute-force-python-O(n2)
class Solution: def longestPalindrome(self, s: str) -> str: res = '' for i in range(len(s)): pos = '' neg = '' for j in range(i, len(s)): pos = pos + s[j] neg = s[j] + neg # print('pos is ', pos) # print('neg is ', neg) if pos == neg and len(pos)>len(res): res = pos return res
longest-palindromic-substring
brute force python O(n^2)
ben_wei
0
3
longest palindromic substring
5
0.324
Medium
225
https://leetcode.com/problems/longest-palindromic-substring/discuss/2784909/Python-O(n)-95-faster-O(n)-Solution
class Solution: def longestPalindrome(self, s: str) -> str: # edge cases: for a char or less return str # 2 pointers, from beginning and end # if they == append to another list. N = len(s) if N <= 1: return s N = 2*N+1 # Position count L = [0] * N L[0] = 0 L[1] = 1 C = 1 # centerPosition R = 2 # centerRightPosition i = 0 # currentRightPosition iMirror = 0 # currentLeftPosition maxLPSLength = 0 maxLPSCenterPosition = 0 start = -1 end = -1 diff = -1 for i in range(2,N): # get currentLeftPosition iMirror for currentRightPosition i iMirror = 2*C-i L[i] = 0 diff = R - i # If currentRightPosition i is within centerRightPosition R if diff > 0: L[i] = min(L[iMirror], diff) # Attempt to expand palindrome centered at currentRightPosition i # Here for odd positions, we compare characters and # if match then increment LPS Length by ONE # If even position, we just increment LPS by ONE without # any character comparison try: while ((i+L[i]) < N and (i-L[i]) > 0) and \ (((i+L[i]+1) % 2 == 0) or \ (s[(i+L[i]+1)//2] == s[(i-L[i]-1)//2])): L[i]+=1 except Exception as e: pass if L[i] > maxLPSLength: # Track maxLPSLength maxLPSLength = L[i] maxLPSCenterPosition = i if i + L[i] > R: C = i R = i + L[i] start = (maxLPSCenterPosition - maxLPSLength) // 2 end = start + maxLPSLength - 1 return s[start:end+1]
longest-palindromic-substring
Python O(n) 95% faster O(n) Solution
mahsumkcby
0
11
longest palindromic substring
5
0.324
Medium
226
https://leetcode.com/problems/longest-palindromic-substring/discuss/2777807/Python3-or-O(N2)-or-Easy-To-Understand
class Solution: def longestPalindrome(self, A: str) -> str: n = len(A) res = "" # for storing longest palindrome resLen = 0 # for storing length of longest palindrome for i in range(0 , n): # for odd length palindrome check l , r = i, i while (l >=0 and r < n and A[l] == A[r]): if (r - l + 1) > resLen: resLen = (r - l + 1) res = A[l : r+1] # decrement l and increment r and check if we can get palindrome of larger size l -= 1 r += 1 # for even length palindrome l , r = i , i + 1 while (l >= 0 and r < n and A[l] == A[r]): if (r - l + 1) > resLen: resLen = (r - l + 1) res = A[l : r+1] # decrement l and increment r and check if we can get palindrome of larger size l -= 1 r += 1 return res
longest-palindromic-substring
Python3 | O(N2) | Easy To Understand
vishal7085
0
2
longest palindromic substring
5
0.324
Medium
227
https://leetcode.com/problems/longest-palindromic-substring/discuss/2755339/Simple-Python-Solution
class Solution: def longestPalindrome(self, s: str) -> str: res = "" resLen = 0 for i in range(len(s)): # odd cases l, r = i, i while l >= 0 and r < len(s) and s[l] == s[r]: if (r-l+1)>resLen: res = s[l:r+1] resLen = r-l+1 l-=1 r+=1 # even cases l, r = i, i+1 while l >= 0 and r < len(s) and s[l] == s[r]: if (r-l+1 )> resLen: res = s[l:r+1] resLen = r-l+1 l-=1 r+=1 return res
longest-palindromic-substring
Simple Python Solution
ekomboy012
0
18
longest palindromic substring
5
0.324
Medium
228
https://leetcode.com/problems/longest-palindromic-substring/discuss/2752656/Palindromic-Subtring-(Best-90-by-Memory)
class Solution: def longestPalindrome(self, s: str) -> str: self.res = ""; self.resLen = 0; for i in range(len(s)): self.getPalindrome(s,i,i); self.getPalindrome(s,i,i+1); return self.res; def getPalindrome(self,s,l,r): while l >= 0 and r < len(s) and s[l] == s[r]: if (r - l + 1) > self.resLen: self.res = s[l:r+1]; self.resLen = len(self.res); l -= 1; r += 1;
longest-palindromic-substring
Palindromic Subtring (Best 90% by Memory)
mohidk02
0
13
longest palindromic substring
5
0.324
Medium
229
https://leetcode.com/problems/zigzag-conversion/discuss/817306/Very-simple-and-intuitive-O(n)-python-solution-with-explanation
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s row_arr = [""] * numRows row_idx = 1 going_up = True for ch in s: row_arr[row_idx-1] += ch if row_idx == numRows: going_up = False elif row_idx == 1: going_up = True if going_up: row_idx += 1 else: row_idx -= 1 return "".join(row_arr)
zigzag-conversion
Very simple and intuitive O(n) python solution with explanation
wmv3317
96
3,000
zigzag conversion
6
0.432
Medium
230
https://leetcode.com/problems/zigzag-conversion/discuss/791453/90-faster-and-90-less-space-%2B-explanation
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows < 2: return s i = 0 res = [""]*numRows # We will fill in each line in the zigzag for letter in s: if i == numRows-1: # If this is the last line in the zigzag we go up grow = False elif i == 0: #Otherwise we go down grow = True res[i] += letter #Add the letter to its row i = (i+1) if grow else i-1 # We increment (add 1) if grow is True, # and decrement otherwise return "".join(res) # return the joined rows
zigzag-conversion
90% faster and 90% less space + explanation
MariaMozgunova
27
1,600
zigzag conversion
6
0.432
Medium
231
https://leetcode.com/problems/zigzag-conversion/discuss/2709075/97-BEATED!
class Solution: def convert(self, s: str, numRows: int) -> str: list_of_items = [[] for i in range(numRows)] DOWN = -1 i = 0 if numRows == 1: return s for char in s: list_of_items[i].append(char) if i == 0 or i == numRows - 1: DOWN *= -1 i += DOWN list_of_items = list(chain(*list_of_items)) return ''.join(list_of_items)
zigzag-conversion
97% BEATED!
lil_timofey
2
435
zigzag conversion
6
0.432
Medium
232
https://leetcode.com/problems/zigzag-conversion/discuss/1645784/Python3-8-Lines-or-Clean-%2B-Simple-Solution-or-Time-O(n)-or-Space-O(1)
class Solution: def convert(self, s: str, numRows: int) -> str: rows, direction, i = [[] for _ in range(numRows)], 1, 0 for ch in s: rows[i].append(ch) i = min(numRows - 1, max(0, i + direction)) if i == 0 or i == numRows - 1: direction *= -1 return ''.join(''.join(row) for row in rows)
zigzag-conversion
[Python3] 8 Lines | Clean + Simple Solution | Time O(n) | Space O(1)
PatrickOweijane
2
410
zigzag conversion
6
0.432
Medium
233
https://leetcode.com/problems/zigzag-conversion/discuss/2216401/O(n)-O(n)-A-simple-Python3-solution-to-an-annoyingly-confusing-problem
class Solution: def convert(self, s: str, numRows: int) -> str: # rules for columns that have a diagonal diagcols = max(numRows-2,1) if numRows>2 else 0 # return diagcols grid = [""]*numRows # while the string isn't empty while s: # insert characters 1 by 1 into each row for index in range(numRows): if s: grid[index] += s[0] s = s[1:] # insert 1 character into each appropriate designated diagonal row, starting from the bottom for index in range(diagcols): if s: grid[diagcols-index] += s[0] s = s[1:] return ''.join(grid)
zigzag-conversion
O(n), O(n) A simple Python3 solution to an annoyingly confusing problem
StackingFrog
1
115
zigzag conversion
6
0.432
Medium
234
https://leetcode.com/problems/zigzag-conversion/discuss/727686/Python3Simple-implementation-less-than-97.89
class Solution: def convert(self, s: str, numRows: int) -> str: length = len(s) if numRows == 1 or numRows >= length: return s step = 2*numRows - 2 ret = "" for i in range(0, numRows): j = i step_one = step - 2*i while j < length: ret += s[j] if i == 0 or i == numRows-1: j += step else: j += step_one #If it's not first or last row, you need to change step after get one character step_one = step - step_one return ret
zigzag-conversion
[Python3]Simple implementation less than 97.89%
abclzm1989
1
225
zigzag conversion
6
0.432
Medium
235
https://leetcode.com/problems/zigzag-conversion/discuss/2846241/Python-3-solution
class Solution: def convert(self, s: str, numRows: int) -> str: actual_row = 0 actual_col = 0 s = [letter for letter in s] matriz = [[0]*(len(s)) for _ in range(numRows)] while s: if actual_row == 0: for row in range(numRows): if not s: break matriz[row][actual_col] = s.pop(0) actual_row = row if numRows == 1: actual_col+=1 else: actual_col+=1 actual_row-=1 if actual_row > 0: matriz[actual_row][actual_col] = s.pop(0) final_string = "" for row in matriz: for letter in row: if letter != 0: final_string+=letter return final_string
zigzag-conversion
Python 3 solution
user0106Ez
0
2
zigzag conversion
6
0.432
Medium
236
https://leetcode.com/problems/zigzag-conversion/discuss/2827899/Python-Solution-Using-Dictionnary
class Solution: def convert(self, s: str, numRows: int) -> str: numCols = (numRows * 2) - 1 d = {} i = 0 col = 0 row = 0 zig = numRows while i < len(s): r = abs(row) d[r] = d.get(r, '') + s[i] del r i += 1 row -= 1 if row == 0: col += 1 if zig == 1: col += 1 zig = numRows if abs(row) == numRows: row = (numRows - 2) zig = 1 col += 1 return ''.join(d.values()) ''' example for numRows=4 using 2D Matrix 0 0,0 1 1,0 2 2,0 3 3,0 4 2,1 + 5 1,2 + 6 0,3 7 1,3 8 2,3 9 3,3 10 2,4 11 1,5 12 0,6 13 1,6 '''
zigzag-conversion
Python Solution Using Dictionnary
chiboubys
0
2
zigzag conversion
6
0.432
Medium
237
https://leetcode.com/problems/zigzag-conversion/discuss/2813961/6.-Zigzag-Conversion-Python-solution-with-explanation-or-Iterate-array-in-zigzag-order
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s skip = (2 * numRows) - 2 res = [] for i in range(numRows): # use i to iterate vertically j = 0 # use j to iterate horizontally while i + j < len(s): res.append(s[j + i]) # gives index of the current iteration sec = (j - i) + skip # due to the nature of the zigzag, there would be a second character in the zigzag if its between second row and second to last row if i != 0 and i != numRows - 1 and sec < len(s): # check if the row isn't the first or last and if the second element calculated isn't larger than the length of s res += s[sec] j += skip # iterate to the next element in the row when in zigzag form return "".join(res)
zigzag-conversion
6. Zigzag Conversion - Python solution with explanation | Iterate array in zigzag order
jonjon98
0
3
zigzag conversion
6
0.432
Medium
238
https://leetcode.com/problems/zigzag-conversion/discuss/2809942/Python-slick-solution-using-generator
class Solution: def convert(self, s: str, numRows: int) -> str: # I will use numRows = 4 to provide examples here # There is nothing to do if numRows == 1 if numRows == 1: return s # Example: for n=4, generator yields numbers in pattern: # 0 1 2 3 2 1 0 1 2 3 . . . # yield works as return but the function doesn't stop entirely, # instead it pauses until we call next() again def generator(n): while True: for i in range(n-1): yield i for j in range(n-1,0,-1): yield j # create a new generator gen = generator(numRows) # Using List Comprehension to create # a list of k lines where k = numRows lines = ["" for k in range(numRows)] # We append char s[0] to line lines[0] # char s[1] to line lines[1] # char s[2] to line lines[2] # char s[3] to line lines[3] # char s[4] to line lines[2] # char s[5] to line lines[1] and so on for char in s: lines[next(gen)] += char # Finally, we stitch the lines together to get the desired string return "".join(lines)
zigzag-conversion
Python slick solution using generator
nbashkir
0
4
zigzag conversion
6
0.432
Medium
239
https://leetcode.com/problems/zigzag-conversion/discuss/2804719/Clean-Python-code
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s res = [""] * numRows cnt, period = 0, 2*numRows-2 for i in range(len(s)): if cnt < numRows: res[cnt] += s[i] else: res[period-cnt] += s[i] cnt = (cnt + 1) % period return "".join(res)
zigzag-conversion
Clean Python code
codebreakblock
0
7
zigzag conversion
6
0.432
Medium
240
https://leetcode.com/problems/zigzag-conversion/discuss/2802918/Simple-Python-Solution
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s row_map = {row:"" for row in range(1,numRows+1)} row = 1 down = True for c in s: row_map[row] += c if row == 1 or ((row < numRows) and down): row += 1 down = True else: row -= 1 down = False converted = "" for row in row_map: converted += row_map[row] return converted
zigzag-conversion
Simple Python Solution
ekomboy012
0
4
zigzag conversion
6
0.432
Medium
241
https://leetcode.com/problems/zigzag-conversion/discuss/2801123/Easy-to-Understand-O(n)-space-and-time-complexity-solution
class Solution: def convert(self, s: str, numRows: int) -> str: direction, row = "positive", -1 rows = [""] * numRows for char in s: row += 1 if direction is "positive" else -1 rows[row] += char if row < 1: direction = "positive" if row == numRows - 1: direction = "negative" return "".join(rows)
zigzag-conversion
Easy to Understand O(n) space, and time complexity solution
Henok2011
0
8
zigzag conversion
6
0.432
Medium
242
https://leetcode.com/problems/zigzag-conversion/discuss/2800084/Python-3-easy-solution
class Solution: def convert(self, s: str, numRows: int) -> str: zigzag = [""] * numRows row_num = 0 dirn = 1 for c in list(s): zigzag[row_num] += c if(row_num >= numRows-1): dirn = -1 elif row_num <= 0: dirn = 1 row_num += dirn return "".join(zigzag)
zigzag-conversion
Python 3 easy solution
pranjal51193
0
5
zigzag conversion
6
0.432
Medium
243
https://leetcode.com/problems/zigzag-conversion/discuss/2790733/Simple-solution-in-python-for-any-interested
class Solution: def convert(self, s: str, numRows: int) -> str: ###### Empty/Trivial case######## if len(s) <2 or s == "" or s == None or numRows == 1: return s ################################# ret = "" rows = list() for i in range(0,numRows): rows.append("") flag = 0 rowCount = 0 for i in range(0,len(s)): rows[rowCount] = rows[rowCount] + s[i] ##handles increasing rows or down the zigzag if flag == 0 and rowCount < (numRows-1): rowCount +=1 elif flag == 0 and rowCount <=(numRows-1): rowCount -=1 flag = 1 ############################################# ##handles decreasing rows or going up the zigzag elif flag == 1 and rowCount > 0: rowCount -=1 elif flag == 1 and rowCount == 0: rowCount +=1 flag = 0 for i in range(0,len(rows)): print("row "+str(i)+" =" +rows[i]) ret = ret + rows[i] #mistyped ret+=blah and it was causing issues return ret
zigzag-conversion
Simple solution in python for any interested
yqd5143
0
3
zigzag conversion
6
0.432
Medium
244
https://leetcode.com/problems/zigzag-conversion/discuss/2790431/Very-Easy-level-mapping-solution-or-95%2B
class Solution: def convert(self, s: str, numRows: int) -> str: if len(s)<=numRows or numRows==1: return s premap=defaultdict(str) i=0 while i<len(s): k=1 while k<numRows and i<len(s): premap[k]+=s[i] k+=1 i+=1 while k>1 and i<len(s): premap[k]+=s[i] k-=1 i+=1 ans='' for v in premap.values(): ans+=v return ans
zigzag-conversion
Very Easy level mapping solution | 95%+
AbhayKadapa007
0
7
zigzag conversion
6
0.432
Medium
245
https://leetcode.com/problems/zigzag-conversion/discuss/2786880/Python-implementation-with-Slice
class Solution: def convert(self, s: str, numRows: int) -> str: n = 2 * numRows - 2 if n == 0: return s ans = s[::n] for i in range(1, n//2): x, y = s[i::n], s[n-i::n] tmp = [None] *len(x+y) tmp[::2] = x tmp[1::2] = y ans += "".join(tmp) ans += s[n//2::n] return ans
zigzag-conversion
Python implementation with Slice
derbuihan
0
4
zigzag conversion
6
0.432
Medium
246
https://leetcode.com/problems/zigzag-conversion/discuss/2782777/Solve-ZigZag-Conversion-in-linear-time
class Solution: def convert(self, s: str, numRows: int) -> str: ans=[] for i in range(numRows): ans.insert(len(ans),[]) i=0 while i<len(s): j=0 while i<len(s) and j<(numRows): ans[j].insert(len(ans[j]),s[i]) i+=1 j+=1 k=0 while i<len(s) and k<(numRows-2): ans[j-k-2].insert(len(ans[j-k-2]),s[i]) i+=1 k+=1 final='' for a in ans: final=final+''.join(a) return final
zigzag-conversion
Solve ZigZag Conversion in linear time
sijan_stha016
0
1
zigzag conversion
6
0.432
Medium
247
https://leetcode.com/problems/zigzag-conversion/discuss/2765011/Quick-line-efficient-solution-in-Py3
class Solution: def convert(self, s: str, numRows: int) -> str: solutionArray = [""] * numRows row = 0 for ele in range(len(s)): if (numRows == 1): return s solutionArray[row] += s[ele] if (row == 0): step = 1 elif (row == (numRows - 1)): step = -1 row += step return ''.join(solutionArray)
zigzag-conversion
Quick, line efficient solution in Py3
mantone6
0
5
zigzag conversion
6
0.432
Medium
248
https://leetcode.com/problems/zigzag-conversion/discuss/2756149/not-simple-python3
class Solution: def convert(self, s: str, numRows: int) -> str: a = [""]*numRows k = 0 boo = True if numRows==1: return s for i in range(len(s)): a[k] += s[i] if boo == True: if k<numRows: if k==(numRows-1): boo = False else: k += 1 else: boo=False if boo == False: if k>0: k -= 1 else: k += 1 boo = True return("".join(a))
zigzag-conversion
not simple python3
meetHadvani
0
4
zigzag conversion
6
0.432
Medium
249
https://leetcode.com/problems/zigzag-conversion/discuss/2755195/Simple-Step-Algorithm-for-zigzag-pattern-using-python
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows <= 1: return s res = "" for i in range(numRows): increment = 2 * (numRows - 1) for j in range(i,len(s),increment): res += s[j] if (i > 0 and i < numRows - 1 and j + increment - 2*i < len(s)): res += s[j + increment - 2*i] return res
zigzag-conversion
Simple Step Algorithm for zigzag pattern using python
mohidk02
0
2
zigzag conversion
6
0.432
Medium
250
https://leetcode.com/problems/zigzag-conversion/discuss/2754172/Concise-Python-Solution-(Beats-95)
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s result = ["" for i in range(numRows)] for i in range(len(s)): if ((i // (numRows-1)) % 2) == 0: result[i % (numRows-1)] += s[i] else: result[(numRows-1) - i % (numRows-1)] += s[i] return "".join(result)
zigzag-conversion
Concise Python Solution (Beats 95%)
ivan_n
0
1
zigzag conversion
6
0.432
Medium
251
https://leetcode.com/problems/zigzag-conversion/discuss/2749707/Simple-Python-Solution-with-Explanation-or-Beginner-Friendly-(Beats-90)
class Solution: def convert(self, s: str, numRows: int) -> str: # If there is only one row, save time and return the string itself if numRows == 1: return s # Create an empty list containing lists, these represent each row result = [] for x in range(numRows): result.append([]) # Using two variables 'direction' and 'ptr', the current row will be tracked # along with which row to add the next variable in. direction = 1 represents down. # direction = 0 represents up direction = 0 ptr = 0 for ch in s: # If its the first row (ptr = 0), we can only move downwards if ptr == 0: result[ptr].append(ch) ptr += 1 direction = 1 continue # If its the last row (ptr = numRows - 1), we can only move upwards if ptr == numRows - 1: result[numRows - 1].append(ch) ptr -= 1 direction = 0 continue # Append and increase/decrease ptr based on direction if direction == 1: result[ptr].append(ch) ptr += 1 else: result[ptr].append(ch) ptr -= 1 # Combine all the lists within the list to get the final string final = '' for x in result: for c in x: final += c return final
zigzag-conversion
Simple Python Solution with Explanation | Beginner Friendly (Beats 90%)
vijaivir
0
9
zigzag conversion
6
0.432
Medium
252
https://leetcode.com/problems/zigzag-conversion/discuss/2744027/O(N)-implementation-using-a-pattern
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s #distance between characters for the top row d0 = 2*numRows - 2 s_res = '' d = 0 #it will store a variable distance for subsequent rows, except top and bottom ones #read 1st row while d < len(s): s_res += s[d] d += d0 #read subsequent rows for i in range(1, numRows-1): d = i cnt = 2*i while d < len(s): s_res += s[d] d += d0 - cnt #calc new variable distance cnt = d0 - cnt #update the variation #read nth row d = numRows - 1 while d < len(s): s_res += s[d] d += d0 return s_res
zigzag-conversion
O(N) implementation using a pattern
nonchalant-enthusiast
0
4
zigzag conversion
6
0.432
Medium
253
https://leetcode.com/problems/zigzag-conversion/discuss/2720579/Easy-to-understand-Python-3-Solution
class Solution: def convert(self, s: str, numRows: int) -> str: zigzag = [""]*numRows goingUp = False i = 0 for ch in s: if not goingUp: zigzag[i] += ch i += 1 if i == numRows: goingUp = True i-=2 continue if goingUp: zigzag[i] += ch i -= 1 if i < 0: goingUp = False i+=2 continue retstr = "" for stri in zigzag: retstr += stri return retstr
zigzag-conversion
Easy to understand Python 3 Solution
thenewkiller
0
5
zigzag conversion
6
0.432
Medium
254
https://leetcode.com/problems/zigzag-conversion/discuss/2719268/Easy-python-3-solutionBeats-89
class Solution: def convert(self, s: str, numRows: int) -> str: b=[''] * numRows i=0 for j in s: b[i]+=j if i==0 and i==(numRows-1): return s elif i==0: swap=0 elif i==(numRows-1): swap=1 if swap==0: i+=1 elif swap==1: i-=1 sol='' for i in b: for j in i: sol+=j return sol
zigzag-conversion
Easy python 3 solution,Beats 89%
joeljoby111
0
2
zigzag conversion
6
0.432
Medium
255
https://leetcode.com/problems/zigzag-conversion/discuss/2676023/Basic-Python-solution-easy-explanation
class Solution: def convert(self, s: str, numRows: int) -> str: newstr = "" if numRows == 1: #one row -> thats just the input string return s #first row j = 0 while j < len(s): newstr += s[j] j += 2 * (numRows - 1) #middle rows for i in range(1, numRows - 1): #i is the row we are constructing down = True #we start by going down the zigzag j = i while j < len(s): newstr += s[j] if down: #count letters in the rows below toadd = 2 * (numRows - (i + 1)) else: #count letters in the rows above #amount of rows above = row index toadd = 2 * i down = not down #reverse direction j += toadd #last row j = numRows - 1 while j < len(s): newstr += s[j] j += 2 * (numRows - 1) return newstr
zigzag-conversion
Basic Python solution - easy explanation
mat1124
0
7
zigzag conversion
6
0.432
Medium
256
https://leetcode.com/problems/zigzag-conversion/discuss/2671340/Simple-Python-Solution-for-6.-Zigzag-Conversion
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows==1: return s ans = ['' for i in range(numRows)] curr = 0 for i in s: ans[curr] += i if curr>=0: curr+=1 if curr==numRows: curr = -2 else: curr-=1 if curr == (numRows+1)*(-1): curr = 1 ans = ''.join(ans) return ans
zigzag-conversion
Simple Python Solution for 6. Zigzag Conversion
Akkishanu
0
4
zigzag conversion
6
0.432
Medium
257
https://leetcode.com/problems/zigzag-conversion/discuss/2667076/Simple-solution
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1 or len(s) == 1: return s res = "" for r in range(numRows): inc = 2 * (numRows - 1) for i in range(r, len(s), inc): res += s[i] if r > 0 and r < numRows - 1 and (i + inc - 2*r) < len(s): res += s[i + inc - (2 * r)] return res
zigzag-conversion
Simple solution
CCsobu
0
1
zigzag conversion
6
0.432
Medium
258
https://leetcode.com/problems/zigzag-conversion/discuss/2640621/python-solution
class Solution: def convert(self, s: str, numRows: int) -> str: if len(s) <= numRows: return s arr = [] s = list(s) for i in range(numRows): arr.append([s.pop(0)]) i -= 1 while i > 0 and s: arr[i].append(s.pop(0)) i -= 1 n = len(s) j = 0 while s: #print(arr) if j < numRows: arr[j].append(s.pop(0)) j += 1 elif j == numRows: j -= 2 while j>0 and s: arr[j].append(s.pop(0)) j -= 1 ans = [] for i in arr: ans.extend(i) return "".join(ans)
zigzag-conversion
python solution
sarthakchawande14
0
5
zigzag conversion
6
0.432
Medium
259
https://leetcode.com/problems/zigzag-conversion/discuss/2628689/Python-double-99
class Solution: def convert(self, s: str, numRows: int) -> str: arr = [""] * numRows if numRows == 1: return s direction = 1 row = 0 for i in range(len(s)): arr[row] += s[i] row += direction if row == numRows - 1: direction = -1 elif row == 0: direction = 1 return "".join(arr)
zigzag-conversion
Python double 99%
babyplutokurt
0
44
zigzag conversion
6
0.432
Medium
260
https://leetcode.com/problems/zigzag-conversion/discuss/2598914/Python-9-line-Simple-Solution
class Solution: def convert(self, s: str, numRows: int) -> str: track = ["" for _ in range(numRows)] period = numRows + max(0, numRows-2) for index, char in enumerate(s): rest = index%period row = rest if rest<numRows else numRows-(rest-numRows)-2 track[row] += char return ''.join(track)
zigzag-conversion
Python 9-line Simple Solution
ParkerMW
0
146
zigzag conversion
6
0.432
Medium
261
https://leetcode.com/problems/zigzag-conversion/discuss/2564910/Easy-python-solution
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s elif numRows ==2: rows=['']*numRows # Stores the letters of each rows for i in range(0,len(s),2): rows[0]+=s[i] for i in range(1,len(s),2): rows[1]+=s[i] return rows[0]+rows[1] else: # For more than 3 rows rows=['']*numRows # Stores the letters of each rows period = 2*numRows-2 for i in range(len(s)): modulus = i%period row_index = modulus if modulus<numRows else 2*numRows-modulus-2 rows[row_index] += s[i] #Concatenate the return value return_value = '' for i in range(numRows): return_value += rows[i] return return_value
zigzag-conversion
Easy python solution
guojunfeng1998
0
53
zigzag conversion
6
0.432
Medium
262
https://leetcode.com/problems/zigzag-conversion/discuss/2564490/easy-python
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s res = [''] * numRows # with function call ''' cur = 0 def increase(num): return num + 1 def decrease(num): return num - 1 pattern = increase for i in range(len(s)): if cur == 0: pattern = increase if cur == numRows - 1: pattern = decrease res[cur] += s[i] cur = pattern(cur) ''' # without function call cur, step = 0, 1 for i in range(len(s)): if cur == 0: step = 1 if cur == numRows - 1: step = -1 res[cur] += s[i] cur += step return ''.join(res)
zigzag-conversion
easy python
MajimaAyano
0
35
zigzag conversion
6
0.432
Medium
263
https://leetcode.com/problems/zigzag-conversion/discuss/2552704/Python3-O(n)-with-explanation
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s res = "" for i in range(numRows): col = i while col < len(s): res += s[col] col_offset = 2 * (numRows - 1) col_next = col + col_offset diag = col + 2 * (numRows - 1 - col % col_offset) if diag != col_next and diag != col and diag < len(s): res += s[diag] col = col_next return res if __name__=="__main__": unittest.main()
zigzag-conversion
[Python3] O(n) with explanation
gdm
0
90
zigzag conversion
6
0.432
Medium
264
https://leetcode.com/problems/zigzag-conversion/discuss/2483938/PYTHON-3-Simple-Clean-approach-beat-99
class Solution: def convert(self, s: str, numRows: int) -> str: all_list = ['']*numRows counter = 0 forward, backward = True, False for i in s: all_list[counter] = all_list[counter] + i if forward: if (counter < numRows-1): counter+=1 else: forward, backward = False, True counter-=1 else: if (counter>0): counter-=1 else: forward, backward = True, False counter+=1 return "".join(all_list)
zigzag-conversion
✅ [PYTHON 3] Simple, Clean approach beat 99% 🏆
girraj_14581
0
170
zigzag conversion
6
0.432
Medium
265
https://leetcode.com/problems/zigzag-conversion/discuss/2416228/Python-Accurate-Fast-Solution-Matrix-Beats-96-oror-Documented
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s # return s, given number of rows is 1 m = [[] for _ in range(numRows)] # create matrix with given rows row = 0 # current row in which char to be add inc = 1 # increment value for c in s: m[row].append(c) # add char to current row row += inc # next current row if row == 0 or row == numRows-1: # if reached at border, inc = -inc # - negate the increment words = ["".join(l) for l in m] # convert rows/(lists of char) into words return "".join(words) # convert words into one string
zigzag-conversion
[Python] Accurate Fast Solution - Matrix - Beats 96% || Documented
Buntynara
0
75
zigzag conversion
6
0.432
Medium
266
https://leetcode.com/problems/zigzag-conversion/discuss/2373621/Easy-Python-3-Solution
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s i = 0 ls = ['']*numRows sign = 1 for ch in s: ls[i]+= ch i+=1*sign if i == numRows: i-=2 sign=-1 if i == -1: i+=2 sign = 1 return ''.join(ls)
zigzag-conversion
Easy Python 3 Solution
harsh30199
0
171
zigzag conversion
6
0.432
Medium
267
https://leetcode.com/problems/zigzag-conversion/discuss/2324247/O(n)-time-O(n)-space-decent-array-solution
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s arr = [[]for _ in range(numRows)] i, row = 0, -1 # row offset by one for proper zigzgging while i < len(s): while row < numRows-1 and i < len(s): row += 1 arr[row].append(s[i]) i += 1 while row > 0 and i < len(s): row -= 1 arr[row].append(s[i]) i += 1 res = '' for row in arr: res += ''.join(row) return res
zigzag-conversion
O(n) time, O(n) space - decent array solution
mfarrill
0
52
zigzag conversion
6
0.432
Medium
268
https://leetcode.com/problems/zigzag-conversion/discuss/2204988/Python3-solution-write-by-AI(Github-Copilot)
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s # create a list of lists rows = [[] for _ in range(numRows)] # print(rows) # iterate through the string # if the index is even, append to the first row # if the index is odd, append to the last row # if the index is even and the row is the last row, append to the first row # if the index is odd and the row is the first row, append to the last row # print(rows) for i, c in enumerate(s): if i % (2 * (numRows - 1)) == 0: rows[0].append(c) elif i % (2 * (numRows - 1)) == 1: rows[numRows - 1].append(c) elif i % (2 * (numRows - 1)) > 1 and i // (2 * (numRows - 1)) % 2 == 0: rows[i // (2 * (numRows - 1))].append(c) else: rows[numRows - i // (2 * (numRows - 1)) - 1].append(c) # print(rows) # join the rows return ''.join([''.join(row) for row in rows]) ```
zigzag-conversion
Python3 solution write by AI(Github Copilot)
aaron17
0
43
zigzag conversion
6
0.432
Medium
269
https://leetcode.com/problems/zigzag-conversion/discuss/2114039/Zigzag-Conversion
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s if len(s) == numRows: return s arr = [[] for i in range(numRows)] row = 0 direction = 1 i = 0 while i < len(s): arr[row] += s[i] if row == len(arr)-1: direction = -1 if row == 0: direction = 1 if direction == 1: row+=1 else: row-=1 i+=1 s = "" for j in arr: for char in j: s+=char return s
zigzag-conversion
Zigzag Conversion
somendrashekhar2199
0
137
zigzag conversion
6
0.432
Medium
270
https://leetcode.com/problems/zigzag-conversion/discuss/2060194/Simple-FSM-or-python
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s temp = [[] for i in range(numRows)] cnt = 0 turnBack = False for i in s: temp[cnt].append(i) if not turnBack: if cnt == numRows - 1: turnBack = not turnBack cnt -= 1 else: cnt += 1 else: if cnt == 0: turnBack = not turnBack cnt += 1 else: cnt -= 1 retval = "" for i in temp: retval += ''.join(i) return retval
zigzag-conversion
Simple FSM | python
skrrtttt
0
95
zigzag conversion
6
0.432
Medium
271
https://leetcode.com/problems/zigzag-conversion/discuss/2005125/8-Lines-Python-Solution-oror-90-Faster-oror-Memory-less-than-80
class Solution: def convert(self, S: str, N: int) -> str: if N==1 or N>=len(S): return S ans=['']*N ; idx=0 ; step=1 for s in S: ans[idx]+=s if idx==0: step=1 elif idx==N-1: step=-1 idx+=step return ''.join(ans)
zigzag-conversion
8-Lines Python Solution || 90% Faster || Memory less than 80%
Taha-C
0
82
zigzag conversion
6
0.432
Medium
272
https://leetcode.com/problems/zigzag-conversion/discuss/1987779/Python3-Simple-linear-solution-with-explanations
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s res = "" for r in range(numRows): increment = 2*(numRows - 1) # offset added to the next element on the same row for i in range(r, len(s), increment): # for each element in the same row res += s[i] # append even-index column element for each row if (r > 0 and r < numRows-1 and i+increment-2*r < len(s)): res += s[i+increment-2*r] # append odd-index column element for middle rows return res
zigzag-conversion
[Python3] Simple linear solution with explanations
leqinancy
0
59
zigzag conversion
6
0.432
Medium
273
https://leetcode.com/problems/zigzag-conversion/discuss/1924411/Zigzag-easily-understandable-Python3-solution
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s #Creating lines list with length numRows lines = [] for i in range(numRows): lines.append([]) #Seperating chars to their corresponding lines idx = 0 flag = True for i,v in enumerate(s): lines[idx].append(v) if idx == numRows-1: flag = False elif idx == 0: flag = True if flag == True: idx += 1 else: idx -= 1 #Combining all chars as required result = '' for i in lines: result += ''.join(i) return result
zigzag-conversion
Zigzag easily understandable Python3 solution
2255141
0
43
zigzag conversion
6
0.432
Medium
274
https://leetcode.com/problems/zigzag-conversion/discuss/1874454/Python3-Solution-using-Dictionary
class Solution: def convert(self, s: str, numRows: int) -> str: dicto = {} row = 1 rowPrev = row for i in range(len(s)): if row in dicto: dicto[row] = dicto[row] + s[i] else: dicto[row] = s[i] if row == numRows or row < rowPrev and row != 1: rowPrev = row row -= 1 elif row == 1 or row > rowPrev: rowPrev = row row += 1 holder = "" theVals = list(dicto.values()) for i in range(len(theVals)): holder = holder + theVals[i] return holder
zigzag-conversion
Python3 Solution using Dictionary
mrpuffie
0
65
zigzag conversion
6
0.432
Medium
275
https://leetcode.com/problems/zigzag-conversion/discuss/1873827/Simple-Python3-Solution
class Solution: def convert(self, s: str, numRows: int) -> str: if numRows == 1: return s a = ['' for i in range(numRows)] c = numRows inc = False for i in s: a[numRows-c] += i # If numRows = 3, the range of numRows-c is [0, 2] as c is in the range of [1, 3] if not inc: c -= 1 if c == 1: inc = True else: c += 1 if c == numRows: inc = False return ''.join(a)
zigzag-conversion
Simple Python3 Solution
rjnkokre
0
54
zigzag conversion
6
0.432
Medium
276
https://leetcode.com/problems/reverse-integer/discuss/1061403/Clean-pythonic-solution
class Solution: def reverse(self, x: int) -> int: retval = int(str(abs(x))[::-1]) if(retval.bit_length()>31): return 0 if x<0: return -1*retval else: return retval
reverse-integer
Clean pythonic solution
njain07
20
3,300
reverse integer
7
0.273
Medium
277
https://leetcode.com/problems/reverse-integer/discuss/2803440/Python-or-Easy-Solution
class Solution: def reverse(self, x: int) -> int: if x not in range(-9,9): x = int(str(x)[::-1].lstrip('0')) if x >= 0 else int(f"-{str(x)[:0:-1]}".lstrip('0')) return x if (x < 2**31-1 and x > -2**31) else 0
reverse-integer
Python | Easy Solution✔
manayathgeorgejames
5
1,500
reverse integer
7
0.273
Medium
278
https://leetcode.com/problems/reverse-integer/discuss/1071721/My-python3-solution
class Solution: def reverse(self, x: int) -> int: number = "".join(reversed(list(str(abs(x))))) result = int("-" + number) if x < 0 else int(number) if -2**31 <= result <= (2**31)-1: return result else: return 0
reverse-integer
My python3 solution
DmitriyL02
5
810
reverse integer
7
0.273
Medium
279
https://leetcode.com/problems/reverse-integer/discuss/670499/Python-line-by-line-explanation
class Solution: def reverse(self, x: int) -> int: # first convert it to string x = str(x) # if less than zero if (int(x)<0) : # first character is "-", so let's retain it # reverse the rest of the characters, then add it up using "+" # convert it back to integer x = int(x[0]+x[1:][::-1]) # if it is zero or more else: # proceed to reverse the characters and convert back to integer x =int(x[::-1]) # if they are -2^31 or 2^31 - 1, return 0. Else, return x return x if -2147483648 <= x <= 2147483647 else 0
reverse-integer
Python line by line explanation
derekchia
5
738
reverse integer
7
0.273
Medium
280
https://leetcode.com/problems/reverse-integer/discuss/1645810/Python3-Checks-Overflow-or-Time-O(logx)-or-Space-O(1)-or-Abiding-by-all-Rules
class Solution: def reverse(self, x: int) -> int: sign = -1 if x < 0 else 1 x = abs(x) maxInt = (1 << 31) - 1 res = 0 while x: if res > (maxInt - x % 10) // 10: return 0 res = res * 10 + x % 10 x //= 10 return sign * res
reverse-integer
[Python3] Checks Overflow | Time O(logx) | Space O(1) | Abiding by all Rules
PatrickOweijane
4
367
reverse integer
7
0.273
Medium
281
https://leetcode.com/problems/reverse-integer/discuss/1270724/Python-Simple-Solution-Easy-to-Read
class Solution: def reverse(self, x: int) -> int: negative = x < 0 ans = 0 if negative: x = x*-1 while x > 0: rem = x % 10 ans = (ans*10)+rem x = x // 10 if negative: ans = ans*-1 if ans > (2**31)-1 or ans < (-2)**31: return 0 else: return ans
reverse-integer
Python Simple Solution, Easy to Read
Khonshu
3
436
reverse integer
7
0.273
Medium
282
https://leetcode.com/problems/reverse-integer/discuss/1048717/Clean-and-Elegant-Python-Solution-with-Overflow-Handled
class Solution: def reverse(self, x: int) -> int: if x == 0: return 0 reversed_integer = 0 sign = 1 if x > 0 else -1 x = abs(x) while x != 0: current_number = x % 10 if reversed_integer * 10 + current_number > (2 **31) or reversed_integer * 10 + current_number < ((-2 ** 31) - 1): return 0 reversed_integer = reversed_integer * 10 + current_number x //= 10 return reversed_integer * sign
reverse-integer
Clean and Elegant Python Solution with Overflow Handled
jdshah
3
268
reverse integer
7
0.273
Medium
283
https://leetcode.com/problems/reverse-integer/discuss/972410/Python3
class Solution: def reverse(self, x: int) -> int: x = ','.join(str(x)).split(',') sign = x.pop(0) if not x[0].isalnum() else None x = ''.join(x[::-1]) res = sign+x if sign else x res = int(res) return res if -1*pow(2, 31) < res < pow(2, 31)-1 else 0
reverse-integer
Python3
mailolumide
3
493
reverse integer
7
0.273
Medium
284
https://leetcode.com/problems/reverse-integer/discuss/2387574/Solution-that-respects-the-signed-32-bit-integer-constraint
class Solution: def reverse(self, x: int) -> int: if x == -2147483648: # -2**31 return 0 # -8463847412 is not a valid input # hence result will never be -2147483648 # so we can work with positiv integers and multiply by the sign at the end s = (x > 0) - (x < 0) # sign of x x *= s max_int = 2147483647 # 2**31-1 result = 0 while x: if result <= max_int//10: result *= 10 else: return 0 if result <= max_int-(x%10): result += x%10 else: return 0 x //= 10 return s*result
reverse-integer
Solution that respects the signed 32-bit integer constraint
SpacePower
2
243
reverse integer
7
0.273
Medium
285
https://leetcode.com/problems/reverse-integer/discuss/2323570/Python-oror-Two-Solutions-(Math-and-String)-with-explanations
class Solution: def reverse(self, x: int) -> int: pn = 1 if x < 0 : pn = -1 x *= -1 x = int(str(x)[::-1]) * pn #^Convert integer into string and reverse using slicing and convert it back to integer return 0 if x < 2**31 * -1 or x > 2**31 -1 else x
reverse-integer
Python || Two Solutions (Math and String) with explanations
zhibin-wang09
2
264
reverse integer
7
0.273
Medium
286
https://leetcode.com/problems/reverse-integer/discuss/2323570/Python-oror-Two-Solutions-(Math-and-String)-with-explanations
class Solution: def reverse(self, x: int) -> int: ans,negative = 0,False if x < 0: negative = True x *= -1 while x > 0: ans *= 10 #Increse the length of answer mod = int(x % 10) #Obtain last digit ans += mod #Add last digit to answer x = int(x /10) #Remove last digit #^Obtain the last digit of x then move it to ans until x = 0. return 0 if ans > 2**31-1 or ans < 2**31 *-1 else -ans if negative else ans
reverse-integer
Python || Two Solutions (Math and String) with explanations
zhibin-wang09
2
264
reverse integer
7
0.273
Medium
287
https://leetcode.com/problems/reverse-integer/discuss/2318304/Python-Solution-Faster-than-96.24
class Solution: def reverse(self, x: int) -> int: sign = 1 if x < 0: sign = -1 x *= -1 x = int(str(x)[::-1]) if x > 2**31-1 or x < 2**31 * -1: return 0 return sign * x
reverse-integer
Python Solution Faster than 96.24%
zip_demons
2
313
reverse integer
7
0.273
Medium
288
https://leetcode.com/problems/reverse-integer/discuss/1486100/Python3-oror-Simplest-and-Valid-oror-With-Explanation
class Solution: def reverse(self, x: int) -> int: # initiate answer as zero # the way we are gonna solve this is by understanding the simple math behind reversing an integer # the objective is to be able to code the mathematical logic; which is why the string approach is totally rubbish and invalid and not the right approach to coding ans = 0 # coding for negative integer negative = x<0 if negative: x = x*-1 # the logic while x>0: rem = x%10 ans = (ans*10)+rem x = x//10 # edge case if ans > (2**31)-1 or ans < (-2)**31: return 0 # negative int elif negative: return ans*-1 else: return ans
reverse-integer
Python3 || Simplest and Valid || With Explanation
ajinkya2021
2
471
reverse integer
7
0.273
Medium
289
https://leetcode.com/problems/reverse-integer/discuss/1364007/99.55-Faster-Python-O(n)-Easily-understandable
class Solution: def reverse(self, x: int) -> int: if(x>0): a = str(x) a = a[::-1] return int(a) if int(a)<=2**31-1 else 0 else: x=-1*x a = str(x) a = a[::-1] return int(a)*-1 if int(a)<=2**31 else 0
reverse-integer
99.55% Faster, Python, O(n), Easily understandable
unKNOWN-G
2
1,200
reverse integer
7
0.273
Medium
290
https://leetcode.com/problems/reverse-integer/discuss/2796506/Python-Simple-Python-Solution-36-ms-faster-than-91.38
class Solution: def reverse(self, x: int) -> int: def reverse_signed(num): sum=0 sign=1 if num<0: sign=-1 num=num*-1 while num>0: rem=num%10 sum=sum*10+rem num=num//10 if not -2147483648<sum<2147483647: return 0 return sign*sum return reverse_signed(x)
reverse-integer
[ Python ] 🐍🐍 Simple Python Solution ✅✅36 ms, faster than 91.38%
sourav638
1
103
reverse integer
7
0.273
Medium
291
https://leetcode.com/problems/reverse-integer/discuss/2659747/Python-O(n)-Time-Solution-with-full-working-explanation
class Solution: # Time: O(n) and Space: O(1) def reverse(self, x: int) -> int: MIN = -2147483648 # -2^31 MAX = 2147483647 # 2^31 - 1 res = 0 while x: # Loop will run till x have some value either than 0 and None digit = int(math.fmod(x, 10)) x = int(x / 10) if res > MAX // 10 or (res == MAX // 10 and digit >= MAX % 10): return 0 if res < MIN // 10 or (res == MIN // 10 and digit <= MIN % 10): return 0 res = (res * 10) + digit return res
reverse-integer
Python O(n) Time Solution with full working explanation
DanishKhanbx
1
233
reverse integer
7
0.273
Medium
292
https://leetcode.com/problems/reverse-integer/discuss/2275852/Python3-Math-solution
class Solution: def reverse(self, x: int) -> int: if x == 0: return 0 elif x < 0: sign = -1 x = abs(x) flag = True else: sign = 1 flag = False ans = 0 digits = int(math.log10(x)) # nubmer of digits - 1 for i in range(digits + 1): ans += (10 ** (digits - i) * (int(x / (10 ** i)) % 10)) if ans > 2 ** 31 - 1: return 0 return ans if not flag else sign * ans
reverse-integer
Python3 Math solution
frolovdmn
1
56
reverse integer
7
0.273
Medium
293
https://leetcode.com/problems/reverse-integer/discuss/2082744/Python3-Runtime%3A-O(n)-oror-O(n)-Runtime%3A-34ms-86.01
class Solution: def reverse(self, x: int) -> int: return self.reverseIntegerByList(x) # O(n) || O(1) 34ms 86.01% def reverseIntegerByList(self, value): if value == 0:return value isNeg = value < 0 value = abs(value) numList = list() newReverseNumber = 0 while value > 0: k = value % 10 newReverseNumber = newReverseNumber * 10 + k value //= 10 if newReverseNumber >= 2**31 or newReverseNumber >= 2**31 - 1: return 0 return newReverseNumber if not isNeg else -newReverseNumber # Brute force # O(n) || O(m) 37ms 76.28% # m stands for making it string def reverseIntegerByString(self, value): isNeg = value < 0 strVal = str(abs(value)) strVal = int(strVal[::-1]) if strVal >= 2**31 or strVal >= 2**31 - 1: return 0 return -strVal if isNeg else strVal
reverse-integer
Python3 Runtime: O(n) || O(n) Runtime: 34ms 86.01%
arshergon
1
101
reverse integer
7
0.273
Medium
294
https://leetcode.com/problems/reverse-integer/discuss/2025235/Python-compact-solution
class Solution: def reverse(self, x: int) -> int: if x > -1: return int(str(x)[::-1]) if int(str(x)[::-1]) < 2147483647 else 0 else: return int("-"+str(abs(x))[::-1]) if int("-"+str(abs(x))[::-1]) > -2147483647 else 0
reverse-integer
Python compact solution
Yodawgz0
1
185
reverse integer
7
0.273
Medium
295
https://leetcode.com/problems/reverse-integer/discuss/1863788/python3-O(N)
class Solution: def reverse(self, x: int) -> int: sign = 1 if x >= 0 else -1 s = str(x*sign) res = int(s[::-1])*sign return 0 if(-2**31 > res or res > (2**31)-1) else res
reverse-integer
[python3] O(N)
Rahul-Krishna
1
70
reverse integer
7
0.273
Medium
296
https://leetcode.com/problems/reverse-integer/discuss/1837832/Python-Simple-Slution
class Solution: def reverse(self, x: int) -> int: a = 1 if x < 0: a = -1 x = abs(x) s = 0 while x: s *= 10 s += x%10 x //= 10 s = a*s if s < -2**31 or s>2**31-1: return 0 return s
reverse-integer
[Python] Simple Slution
zouhair11elhadi
1
82
reverse integer
7
0.273
Medium
297
https://leetcode.com/problems/reverse-integer/discuss/1791782/Python-Solution-(only-4-Lines-of-Code)
class Solution: def reverse(self, x: int) -> int: flage=False if(x<0): flage=True return((-int(str(abs(x))[::-1]) if flage else int(str(abs(x))[::-1])) if(-231<int(str(abs(x))[::-1])<231) else 0)
reverse-integer
Python Solution (only 4 Lines of Code)
aswin_thumati
1
178
reverse integer
7
0.273
Medium
298
https://leetcode.com/problems/reverse-integer/discuss/1645357/Python-runtime-99.84-memory-98.89
class Solution(object): def reverse(self, x): if x < 0: y = 0-int(str(abs(x))[::-1]) if y <= -(pow(2,31)): return 0 return y else: y = int(str(x)[::-1]) if y >= pow(2,31)-1: return 0 return y
reverse-integer
Python runtime 99.84%, memory 98.89%
cwrli
1
205
reverse integer
7
0.273
Medium
299