Given an array nums of integers, you can perform operations on the array.

In each operation, you pick any nums[i] and delete it to earn nums[i] points.  After, you must delete every element equal to nums[i] - 1 or nums[i] + 1.

You start with 0 points.  Return the maximum number of points you can earn by applying such operations.


Example 1:

Input: nums = [3, 4, 2]
Output: 6
Explanation: 
Delete 4 to earn 4 points, consequently 3 is also deleted.
Then, delete 2 to earn 2 points. 6 total points are earned.



Example 2:

Input: nums = [2, 2, 3, 3, 3, 4]
Output: 9
Explanation: 
Delete 3 to earn 3 points, deleting both 2's and the 4.
Then, delete 3 again to earn 3 points, and 3 again to earn 3 points.
9 total points are earned.



Note:
The length of nums is at most 20000.
Each element nums[i] is an integer in the range [1, 10000].

Difficulty: interview

Starter code:

class Solution:
    def deleteAndEarn(self, nums: List[int]) -> int:
        

Solutions:
class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         count = collections.Counter(nums);#count is a dict [3,4,2]--> {2:1,3:1,4:1}
         prev = None;
         avoid = using = 0;
         for k in sorted(count):
             temp = max(avoid,using)
             if k - 1 != prev:
                 using = k * count[k] + temp
                 avoid = temp
             else:
                 using = k * count[k] + avoid
                 avoid = temp
 
             prev = k
         return max(avoid,using)

class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         if (nums == []):
             return 0
         if (len(nums) == 1):
             return nums[0]
         
         nums.sort()
         numsp = nums[0]
         choose = [0,nums[0]]
         for i in range(1,len(nums)):
           numsc = nums[i]
           if (numsc == numsp):
               choose[1] += numsc
               continue
           elif(numsc == numsp+1):
               temp = choose[0]
               choose[0] = max(choose)
               choose[1] = temp+numsc
               numsp = numsc
           else:
               choose[0] = max(choose)
               choose[1] = choose[0]+numsc
               numsp = numsc
               
         return max(choose)

class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         nums.sort()
         nums.append(-1) #end symbol
         prev_max, cur_max = 0, 0
         prev = -1
         j, i = 0, 0
         while i < len(nums):
             if nums[i] == nums[j]:
                 i += 1
                 continue
             dif = i - j
             temp = dif*nums[j]
             if nums[j] == prev + 1:
                 prev_max, cur_max = cur_max, max(temp + prev_max, cur_max)
             else:
                 prev_max, cur_max = cur_max, temp + cur_max
             prev = nums[j]
             j = i
             i += 1
         return cur_max

class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         if len(nums) == 0: return 0
         upper = max(nums)
         ordered = [0]*(upper+1)
         for i in nums: ordered[i]+=i
             
         ans = [0]*(upper+1)
         ans[1] = ordered[1]    
         for i in range (2,upper+1):
             ans[i] = max(ans[i-1],ans[i-2]+ordered[i])
         
         return ans[upper]

class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         from collections import Counter
         c = Counter(nums)
         n = len(nums)
         pick = {-math.inf:0}
         miss = {-math.inf:0}
         prev = -math.inf
         for (num, freq) in sorted(c.items()):
             if prev == num - 1:
                 pick[num] = miss[num-1] + num*freq
                 miss[num] = max(miss[num-1], pick[num-1])
             else:
                 pick[num] = max(miss[prev], pick[prev]) + num*freq
                 miss[num] = max(miss[prev], pick[prev])
             prev = num
             # print(num, pick, miss)
         return max(pick[prev], miss[prev])

class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         if len(nums) == 0:
             return 0
         
         nums.sort()
         a = [0]*len(nums)
         b = [0]*len(nums)
         k = -1
         a[-1] = nums[-1]
         b[-1] = 0
         for i in range(len(nums)-2, -1, -1):
             print(nums[i], nums[i+1])
             if nums[i] == nums[i+1]-1:
                 a[i] = max(a[k], b[k])+nums[i] if k!=-1 else nums[i]
                 b[i] = max(a[i+1], b[i+1])
             elif nums[i] == nums[i+1]:
                 a[i] = a[i+1]+nums[i]
                 b[i] = b[i+1]
             else:
                 a[i] = max(a[i+1], b[i+1])+nums[i]
                 b[i] = max(a[i+1], b[i+1])
             if nums[i] < nums[i+1]:
                 k = i+1
 
         return(max(a[0], b[0]))

class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """        
         # build a count array for nums
         if len(nums)==0:
             return 0
         
         nums.sort()
         count = collections.Counter(nums)
                 
         take = [0]*(1+nums[-1])
         delete = [0]*(1+nums[-1])
         try:
             take[1] = count[1]
         except KeyError:
             take[1] = 0
 
         for i in range(2,nums[-1]+1):
             print(i)
             try:
                 delete[i] = max(take[i-1], delete[i-1])
                 take[i] = i*count[i] + max(take[i-2], delete[i-1])
             except KeyError:
                 continue
 
         print(take)
         print(delete)
         res = max(take[-1],delete[-1])
         return res