LetCode 127. 单词接龙_python 127. 单词接龙

class Solution {
public:
    int ladderLength(string beginWord, string endWord, vector<string>& wordList) {
        // 单词字典，方便查询
        unordered_set<string> s(wordList.begin(), wordList.end());
        // 记录单词的出现
        unordered_map<string, int> m;
        if (!s.count(endWord))
            return 0;
        m[beginWord] = 1;
        queue<string> q;
        q.push(beginWord);
        // 层序遍历
        while(!q.empty()){
            string word = q.front();
            q.pop();
            for(int i = 0; i < word.length(); ++i){
                string tmp = word;
                for (char j = 'a'; j <= 'z'; ++j){
                    tmp[i] = j;
                    if (s.count(tmp)){
                        if (tmp == endWord)
                            return m[word] + 1;
                        if (!m.count(tmp)){
                            q.push(tmp);
                            m[tmp] = m[word] + 1;
                        }
                    }
                }
            }
        }
        return 0;
    }
};
 
static int x=[](){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();