Code RoomModular multiplicative inverse
HardPrep Room Coding #752

Modular multiplicative inverse

CodingAlgorithms & data structuresSenior–Staff~30 min

Given integers a and m (1 <= a < m <= 10^9), return the modular multiplicative inverse of a modulo m — the integer x in [0, m) such that (a * x) % m == 1. If no inverse exists (because a and m are not coprime), return -1. Do not assume m is prime.

Implement
mod_inverse(a: int, m: int) → int
Examples
in[3,11]out4
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 30 min
InputExpectedGot
[3,11]4not run yetsample