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Word Ladder
Transform one word into another, changing one letter at a time, using only valid dictionary words. It's a shortest-path problem hiding behind a word puzzle—BFS finds the minimum steps. The insight is modeling words as graph nodes where edges connect words that differ by exactly one letter.
Learn this pattern
Arrays and Hashing Interview Questions
Arrays and hashing problems are about fast lookup choices: set for membership, map for attached state, and buckets when counts are bounded. Reach for this family when brute force compares too many pairs or when you need to remember what you saw earlier in one pass.
Meet your coaches
Talk through the problem while you code. Signed-in reps become prep memory for the next session.
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Arrays and Hashing Interview Questions gives you a useful next rep while you are still on your phone.