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127-Word-Ladder.java
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127-Word-Ladder.java
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package java;
class Solution {
public int ladderLength(String beginWord, String endWord, List<String> wordList) {
Map<String, List<String>> adjlist = new HashMap<>();
wordList.add(beginWord);
for(String word:wordList){
StringBuilder string=null;
for(int i=0;i<word.length();i++){
string = new StringBuilder(word);
string.setCharAt(i, '*');
List<String> wordlist = adjlist.getOrDefault(string.toString(), new ArrayList<String>());
wordlist.add(word);
adjlist.put(string.toString(), wordlist);
}
}
Queue<String> queue = new LinkedList<>();
queue.offer(beginWord);
Set<String> visited = new HashSet<>();
visited.add(beginWord);
int step = 1;
StringBuilder string=null;
while(!queue.isEmpty()){
step++;
int size = queue.size();
for(int j=0;j<size;j++){
String str = queue.poll();
for(int i=0;i<str.length();i++){
string = new StringBuilder(str);
string.setCharAt(i, '*');
for(String pat:adjlist.get(string.toString())){
if(pat.equals(endWord)){
return step;
}
if(visited.contains(pat)){
continue;
}
queue.offer(pat);
visited.add(pat);
}
}
}
// step++;
}
return 0;
}
}