题目描述
Given two words (start and end), and a dictionary, find the length of shortest transformation sequence from start to end, such that:
- Only one letter can be changed at a time
- 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 length5.
Note:
- Return 0 if there is no such transformation sequence.
- All words have the same length.
- All words contain only lowercase alphabetic characters.
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- 思路:借助队列实现树的广度遍历。