Given a list of strings words representing an English Dictionary, find the longest word in words that can be built one character at a time by other words in words.  If there is more than one possible answer, return the longest word with the smallest lexicographical order.  If there is no answer, return the empty string.

Example 1:

Input: 
words = ["w","wo","wor","worl", "world"]
Output: "world"
Explanation: 
The word "world" can be built one character at a time by "w", "wo", "wor", and "worl".



Example 2:

Input: 
words = ["a", "banana", "app", "appl", "ap", "apply", "apple"]
Output: "apple"
Explanation: 
Both "apply" and "apple" can be built from other words in the dictionary. However, "apple" is lexicographically smaller than "apply".



Note:
All the strings in the input will only contain lowercase letters.
The length of words will be in the range [1, 1000].
The length of words[i] will be in the range [1, 30].

Difficulty: introductory

Starter code:

class Solution:
    def longestWord(self, words: List[str]) -> str:
        

Solutions:
class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """
         
         result = "";
         wordSet = set(words);
         for word in words:
             if (len(word) > len(result) or len(word) == len(result) and word < result) and all(word[ : i] in wordSet for i in range(1, len(word))):
                 result = word;
                 
         return result;

class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """
         if len(words) == 0:
             return ""
         
         words.sort(key = lambda x: (len(x), x))
         memo = set()
         maxlen = 0
         maxword = ""
         for word in words:
             if len(word) <= 1:
                 memo.add(word)
                 maxlen = 1
                 if maxword == "":
                     maxword = word
             else:
                 if word[:-1] in memo:
                     memo.add(word)
                     if len(word) > maxlen:
                         maxlen = len(word)
                         maxword = word
         
         return maxword


class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """
         words.sort()
         words_set = set([''])
         longest = ''
         
         for word in words:
             if word[:-1] in words_set:
                 words_set.add(word)
                 if len(word) > len(longest):
                     longest = word
         return longest


class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """        
         wset = set([""])
         ans = ""
         for word in sorted(words):            
             if word[:-1] in wset:
                 wset.add(word)
                 if len(word) > len(ans):
                     ans = word        
         return ans
         


class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """
  
         words.sort()
         words_set, longest_word = set(['']), ''
         for word in words:
             if word[:-1] in words_set:
                 words_set.add(word)
                 if len(word) > len(longest_word):
                     longest_word = word
         return longest_word

class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """
         valid = {''}
         for word in sorted(words):
             if word[:-1] in valid:
                 valid.add(word)
         return max(sorted(valid), key = len)

class Solution:
     def longestWord(self, words):
                 
                
         words.sort()
         longest_word=''
         word_list=list()
         words_set=set([''])
         for word in words:
             
             if word[:-1] in  words_set  :
               
                 words_set.add(word)
           
                 if len(longest_word)<len(word):
                     longest_word=word
         
         return longest_word
    


class Solution:
     def longestWord(self, words):
         ret, m = '', {''}
         for w in sorted(words):
             if w[:-1] in m:
                 m.add(w)
                 ret = max(ret, w, key=len)
         return ret


class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """
         wordSet = set(words)
 
         words.sort(key=lambda c: (-len(c), c))
         for word in words:
             if all(word[:k] in wordSet for k in range(1, len(word))):
                 return word
         return ""


class Solution:
     def longestWord(self, words):
         """
         :type words: List[str]
         :rtype: str
         """
         
         words.sort()
         words_set, longest_word = set(['']), ''
         for word in words:
             if word[:-1] in words_set:
                 words_set.add(word)
                 if len(word) > len(longest_word):
                     longest_word = word
         return longest_word