直接BFS.....
有一处搞了很久 发现原来return是转换过程有多少个word... 而不是换了多少个字母
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45 | public class Solution {
public int ladderLength(String beginWord, String endWord, Set<String> wordList) {
HashSet<String> notVisited = new HashSet<String>(wordList);
boolean found = false;
HashSet<String> nextLevel = new HashSet<String>();
HashSet<String> curLevel = new HashSet<String>();
curLevel.add(beginWord);
notVisited.remove(beginWord);
int level = 1;
while (!found && !curLevel.isEmpty()){
if (curLevel.contains(endWord)){
found = true;
}else{
level++;
}
for (String cur:curLevel){
getNextWords(nextLevel, notVisited, cur);
}
HashSet<String> inter = nextLevel;
nextLevel = curLevel;
curLevel = inter;
nextLevel.clear();
}
return found?level:0;
}
public void getNextWords(HashSet<String> nextWord, HashSet<String>notVisited, String current){
char []possible = current.toCharArray();
for (int i = 0; i < possible.length; i++){
char origin = possible[i];
for (char a = 'a'; a <= 'z'; a++){
if (a != origin){
possible[i] = a;
String temp = String.valueOf(possible);
if (notVisited.contains(temp)){
nextWord.add(temp);
notVisited.remove(temp);
}
}
}
possible[i] = origin;
}
}
}
|
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