Java for LeetCode 127 Word Ladder

標籤：

Given two words (beginWord and endWord), and a dictionary, find the length of shortest transformation sequence from beginWord to endWord, such that:

1. Only one letter can be changed at a time
2. Each intermediate word must exist in the dictionary

For example,

Given:
start = "hit"
end = "cog"
dict = ["hot","dot","dog","lot","log"]

As one shortest transformation is "hit" -> "hot" -> "dot" -> "dog" -> "cog",
return its length 5.

解題思路一：

對set進行逐個遍曆，遞迴實現，JAVA實現如下：

static public int ladderLength(String beginWord, String endWord,Set<String> wordDict) {int result = wordDict.size() + 2;Set<String> set = new HashSet<String>(wordDict);if (oneStep(beginWord, endWord))return 2;for (String s : wordDict) {if (oneStep(beginWord, s)) {set.remove(s);int temp = ladderLength(s, endWord, set);if (temp != 0)result = Math.min(result, temp + 1);set.add(s);}}if (result == wordDict.size() + 2)return 0;return result;}public static boolean oneStep(String s1, String s2) {int res = 0;for (int i = 0; i < s1.length(); i++)if (s1.charAt(i) != s2.charAt(i))res++;return res == 1;}

 結果TLE

解題思路二：

 

Java for LeetCode 127 Word Ladder