# Coding Interviews: Graphs

Collapse

AllJavascriptEasyMediumHardVideoPythonCode SolutionJava

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 for 1 <= i <= k is in wordList. Note that beginWord does not need to be in wordList.

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.*