127. Word Ladder ⭐
Hard
A transformation sequence from word beginWord
to word endWord
using a dictionary wordList
is a sequence of words beginWord -> s1 -> s2 -> ... -> sk
such that:
Every adjacent pair of words differs by a single letter.
Every
si
for1 <= i <= k
is inwordList
. Note thatbeginWord
does not need to be inwordList
.sk == endWord
Given two words, beginWord
and endWord
, and a dictionary wordList
, return the number of words in the shortest transformation sequence from beginWord
to endWord
, or 0
if no such sequence exists.
Example 1:
Example 2:
Constraints:
1 <= beginWord.length <= 10
endWord.length == beginWord.length
1 <= wordList.length <= 5000
wordList[i].length == beginWord.length
beginWord
,endWord
, andwordList[i]
consist of lowercase English letters.beginWord != endWord
All the words in
wordList
are unique.
解題
Runtime: 150 ms, faster than 62.69%
Memory Usage: 7.8 MB, less than 46.71%
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