Fast modular multiplication

4 problems from Fast modular multiplication (contest 103399), difficulty -. 2/4 solutions verified against sample I/O.

4 items

Fast modular multiplication

Special | 4 problems | 2/4 verified | Difficulty - | 4m 31s

# Problem Rating Tags Accepted Time ✓
A Fast modular multiplication modulo 32-bit modulus 2m 29s
B Fast modular multiplication modulo 57-bit modulus 27s
C Fast modular multiplication modulo 63-bit modulus 50s ✓
D Fast modular multiplication modulo 64-bit modulus 45s ✓
Practice › Codeforces Solutions › Fast modular multiplication ›

CF 103399A - Fast modular multiplication modulo 32-bit modulus

Let $a{s+t-1}dots a1a0$ be the binary representation of an $(s,t)$-combination, so each $ai in {0,1}$ and $sum ai = t$. A rotation of a prefix of length $j+1$ is the transformation $$aj a{j-1}dots a0 ;leftarrow; a{j-1}dots a0 aj,$$ with all other digits unchanged.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › Fast modular multiplication ›

CF 103399D - Fast modular multiplication modulo 64-bit modulus

We are given two integers and asked to compute their product under a very large modulus, where the modulus is a full 64-bit value.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › Fast modular multiplication ›

CF 103399C - Fast modular multiplication modulo 63-bit modulus

We repeatedly generate triples (x, y, m) using a deterministic XOR-shift RNG. Each triple represents a modular multiplication request where both operands and modulus are close to the limits of 63-bit integers.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › Fast modular multiplication ›

CF 103399B - Fast modular multiplication modulo 57-bit modulus

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codeforces competitive-programming Jul 3, 2026