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Solution: Word Ladder II

Explore the solution to the Word Ladder II problem by understanding how to use breadth-first search to find the shortest transformation paths and depth-first search backtracking to reconstruct all shortest sequences. This lesson helps you grasp a two-phase approach to efficiently find and enumerate all valid shortest word ladders.

Statement

You are given two words, beginWord and endWord, and a dictionary of words called wordList. Your task is to find all the shortest transformation sequences from beginWord to endWord, such that:

  1. Only one letter can be changed at a time.

  2. Each transformed word must exist in the given wordList.

  3. The transformation sequence must begin with beginWord and end with endWord.

Return all the shortest transformation sequences as a list of lists. If no valid transformation exists, return an empty list.

Constraints:

  • 11 \leq ...