Problem · Graph
Determine the Edit Distance in a Word Ladder
Learn this problemProblem statement
Given two words (beginWord and endWord), and a dictionary's word list, find the minimum number of operations needed to change beginWord into endWord.
You can change only one letter at a time, and each intermediate word must exist in the word list. If there is no possible transformation, return None (Python), -1 (Java & C++), null (Javascript).
Function
ladderLength(beginWord: String, endWord: String, wordList: List<String>) → intExamples
Example 1
beginWord = "hit"endWord = "cog"wordList = ["hit", "hot", "dot", "dog", "cog"]return = 4
The transformation sequence can be: hit -> hot -> dot -> dog -> cog, which is 4 steps long.
Example 2
beginWord = "word"endWord = "word"wordList = ["word", "ward"]return = 0
Since the beginWord is the same as the endWord, no transformation is needed, so the number of steps is 0.
Example 3
beginWord = "hit"endWord = "cog"wordList = ["hit", "hot", "dot", "dog"]return = -1
The word cog is not in the list, so there is no possible transformation sequence.