#strings
3 articles
Tries (Prefix Trees)
The data structure powering autocomplete, spell-check, and IP routing — a tree where each edge is a character and every path from the root spells a prefix. Insert, search, and prefix queries all run in O(L) on word length alone, completely independent of how many words you store.
Strings
Strings look like simple text, but they hide a brutal trap: naive concatenation in a loop is O(n²). Learn why, how encoding actually works, and the handful of patterns — sliding window, two pointers, hashing — that solve 80% of string interview problems.
The Sliding Window Pattern
Learn the sliding window technique to solve "longest/shortest/contains" subarray and substring problems in O(n) instead of O(n²). Covers fixed and variable windows, the expand-right-shrink-left template, and the classic bugs.