单词接龙

function ladderLength(beginWord: string, endWord: string, wordList: string[]): number {
    if (!wordList.includes(endWord)) {
        return 0;
    }
    const wordMap: Record<string, string[]> = {
      [beginWord]: []
    }
 
    function setWordMap(word, nextWord, reverse = true) {
      let curWordMap = wordMap[word];
      if (!curWordMap) {
        curWordMap = [];
        wordMap[word] = curWordMap;
      }
      curWordMap.push(nextWord);
      if (reverse) {
        setWordMap(nextWord, word, false);
      }
    }
 
    for (let i = 0; i < wordList.length; i++) {
      const curWord = wordList[i];
      if (isOneEditDistance(beginWord, curWord)) {
        setWordMap(beginWord, curWord);
      }
      for (let j = i + 1; j < wordList.length; j++) {
        const nextWord = wordList[j];
        if (isOneEditDistance(curWord, nextWord)) {
          setWordMap(curWord, nextWord);
        }
      }
    }
    return breadthFirstSearch(wordMap, beginWord, endWord);
};
 
function breadthFirstSearch(wordMap: Record<string, string[]>, beginWord: string, endWord: string): number {
  let queues: string[][] = [[beginWord]];
  let usedWords: string[] = [beginWord];
  while(true) {
    let _queues: string[][] = [];
    for (let i = 0; i < queues.length; i++) {
      const curQueue = queues[i];
      const curWord = curQueue[curQueue.length - 1];
      const nextWords = wordMap[curWord];
      if (nextWords.includes(endWord)) {
        return curQueue.length + 1;
      }
      _queues.push(...nextWords.filter(word => !usedWords.includes(word)).map(word => {
        usedWords.push(word);
        return [...curQueue, word]
      }));
    }
    queues = _queues;
    if (queues.length === 0) {
      return 0; 
    }
  }
}
 
function isOneEditDistance(word1: string, word2: string): boolean {
    if (word1.length !== word2.length) {
        return false;
    }
    let count = 0;
    for (let i = 0; i < word1.length; i++) {
      if (word1[i] !== word2[i]) {
        count++;
      }
    }
    return count === 1;
}