Code RoomLongest repeating substring
HardPrep Room Coding #1375

Longest repeating substring

CodingAlgorithms & data structuresSenior–Staff~40 min

Given a lowercase string s, return the longest substring that appears at least twice in s (occurrences may overlap). If none repeats, return the empty string. For 'banana' the answer is 'ana'. If multiple longest answers exist, returning any one of them is acceptable. Length up to a few thousand.

Implement
longest_dup_substring(s: str) → str
Examples
in["banana"]out"ana"
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 40 min
InputExpectedGot
["banana"]"ana"not run yetsample