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Word Ladder (Shortest Transformation) is a hard coding interview question covering graphs, breadth-first search, strings — the kind asked at FAANG (Facebook/Meta, Apple, Amazon, Netflix, Google) and AI-first companies like Anthropic, OpenAI, and Nvidia.
Given beginWord, endWord, and a wordList, return the length of the shortest transformation sequence from beginWord to endWord, where each step changes exactly one letter and each intermediate word must be in wordList.
Example: beginWord="hit", endWord="cog", wordList=["hot","dot","dog","lot","log","cog"] -> 5
Return 0 if no such sequence exists. Each word has the same length.
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