bidirectional-bfs:

Word Ladder

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.

by lek tin in "algorithm" access_time 2-min read