https://leetcode.com/problems/word-ladder/
class Solution {
public:
int ladderLength(string beginWord, string endWord, unordered_set<string>& wordList) {
if (beginWord == endWord) {
return 1;
}
int count = 2;
int ws = beginWord.length();
queue<string> q;
q.push(beginWord);
wordList.erase(beginWord);
while (!q.empty()) {
int n = q.size();
for (int i = 0; i < n; i++) {
string word = q.front();
q.pop();
for (int ci = 0; ci < ws; ci++) {
char och = word[ci];
for (char nch = 'a'; nch <= 'z'; nch++) {
word[ci] = nch;
if (word == endWord) {
return count;
}
if (wordList.find(word) != wordList.end()) {
q.push(word);
wordList.erase(word);
}
}
word[ci] = och;
}
}
count++;
}
return 0;
}
};
