class Solution:
    def ladderLength(self, beginWord: str, endWord: str, wordList: List[str]) -> int:

        res = 0
        Q = collections.deque()
        Q.append(beginWord)
        Set = set(wordList)

        if endWord not in Set:
            return 0

        while(Q):
            res += 1
            n = len(Q)
            for i in range(n):
                word = Q.popleft()

                for j in range(len(word)):
                    for ch in 'abcdefghijklmnopqrstuvwxyz':
                        word_copy = word[:j] + ch + word[j+1:]
                        if str(word_copy) == endWord:
                            return res + 1

                        if str(word_copy) in Set:
                            Q.append(str(word_copy))
                            Set.remove(str(word_copy))
        return 0