Code RoomLongest common substring
HardPrep Room Coding #1367

Longest common substring

CodingAlgorithms & data structuresSenior–Staff~35 min

Given two lowercase strings a and b, return the length of their longest common substring (a contiguous run appearing in both). Strings are up to a few thousand characters. Return 0 if there is no common substring.

Implement
longest_common_substring(a: str, b: str) → int
Examples
in["abcde","zbcdf"]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
["abcde","zbcdf"]3not run yetsample