Word Ladder Solution | BFS | Python

wordLadder.py

class Solution:
    def ladderLength(self, beginWord: str, endWord: str, wordList: List[str]) -> int:
        #TC = O(M^2 * N)  where M is the length of the words we jump on and N is the length of wordList
        #SC = O(M^2 * N) where M is for words we jump on and N is the wordlist space

        if endWord not in wordList:
            return 0

        q = deque([beginWord])

        available = set(wordList)
        jumps = 0

        while q:
            jumps+=1
            n = len(q)

            for i in range(n):
                currWord = q.popleft()

                if currWord == endWord: return jumps

                for j in range(len(currWord)):
                    orgC = currWord[j]
                    
                    for alpha in range(26):
                        currWord = currWord[:j] + chr(97 + alpha) + currWord[j+1:]
                        
                        if(currWord in available):
                            q.append(currWord)
                            available.remove(currWord)
                    
                    currWord = currWord[:j]+orgC+currWord[j+1:]

        return 0