0127-word-ladder.adoc

127. Word Ladder

LeetCode - Word Ladder

通过 Word Ladder - LeetCode 讲解，竟然可以抽象成无向无权图，然后通过 Queue 将其串联起来，实在好精巧。

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

• Only one letter can be changed at a time.

• Each transformed word must exist in the word list. Note that beginWord is not a transformed word.

Note:

• Return 0 if there is no such transformation sequence.

• All words have the same length.

• All words contain only lowercase alphabetic characters.

• You may assume no duplicates in the word list.

• You may assume beginWord and endWord are non-empty and are not the same.

Example 1:

Input:
beginWord = "hit",
endWord = "cog",
wordList = ["hot","dot","dog","lot","log","cog"]

Output: 5

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

Example 2:

Input:
beginWord = "hit"
endWord = "cog"
wordList = ["hot","dot","dog","lot","log"]

Output: 0

Explanation: The endWord "cog" is not in wordList, therefore no possible* *transformation.

link:{sourcedir}/_0127_WordLadder.java[role=include]