Asked at

Word Ladder

Hard
VerifiedBFSGraphString Matching~35 min

Transform beginWord into endWord by changing one letter at a time. Every intermediate word must be in wordList, and each step changes exactly one character.

Return the number of words in the shortest such sequence (counting both ends), or 0 if none exists. The input arrives as a single object { beginWord, endWord, wordList }.

Examples

in{ beginWord: "hit", endWord: "cog", wordList: ["hot","dot","dog","lot","log","cog"] }
out5

hit→hot→dot→dog→cog has 5 words.

in{ beginWord: "hit", endWord: "cog", wordList: ["hot","dot","dog","lot","log"] }
out0

endWord is not in the list, so no sequence exists.

Constraints

  • All words have the same length.
  • 1 ≤ word.length ≤ 10
  • Words contain lowercase letters only.
  • beginWord may or may not be in wordList.

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