Code RoomLongest duplicate substring
HardPrep Room Coding #649

Longest duplicate substring

CodingAlgorithms & data structuresSenior–Staff~35 min

Given a string s, return the length of the longest substring that appears at least twice in s (the two occurrences may overlap). If no character repeats in a way that yields a duplicated substring, return 0. For example, "banana" has "ana" of length 3 appearing twice. The string can be up to a few thousand characters, so the intended approach binary-searches the answer length and uses hashing to test each candidate length.

Implement
longest_dup_substring_len(s: str) → int
Examples
in["banana"]out3
What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

0:00 of about 35 min
InputExpectedGot
["banana"]3not run yetsample