Add 127_Word_Ladder.java

Author: Sean Prashad

Strings/127_Word_Ladder.java

@@ -0,0 +1,41 @@
+class Solution {
+ public int ladderLength(String beginWord, String endWord, List<String> wordList) {
+ Set<String> dict = new HashSet<>(wordList);
+ Queue<String> q = new LinkedList<>();
+ int level = 1;
+
+ q.offer(beginWord);
+
+ while (!q.isEmpty()) {
+ int size = q.size();
+
+ for (int i = 0; i < size; i++) {
+ char[] letters = q.poll().toCharArray();
+
+ for (int j = 0; j < letters.length; j++) {
+ char tmp = letters[j];
+
+ for (char c = 'a'; c <= 'z'; c++) {
+ letters[j] = c;
+
+ String modifiedWord = new String(letters);
+
+ if (dict.remove(modifiedWord)) {
+ if (modifiedWord.equals(endWord)) {
+ return ++level;
+ }
+ q.offer(modifiedWord);
+ dict.remove(modifiedWord);
+ }
+ }
+
+ letters[j] = tmp;
+ }
+ }
+
+ ++level;
+ }
+
+ return 0;
+ }
+}