What is the time complexity of trie (prefix tree)?

Worst case O(length of the key). Space complexity is O(total characters × alphabet). Independent of how many words are stored - only key length matters.

Trie (prefix tree)

medium

No node stores a word - a word exists when a path of edges spells it and ends on a node flagged as a word end. Shared prefixes cost nothing extra, which is what makes autocomplete cheap.

Worst O(length of the key)Space O(total characters × alphabet)

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Where to go next

Binary search tree

medium

Insert, search and the three cases of deletion.

KMP pattern matching

hard

The text pointer never moves backwards.

Hash table with chaining

medium

Collisions share a bucket, and load factor is everything.