5 subtopics · 22 problems
Mathematics & Number Theory
Divisibility, primes, GCD/LCM, modular arithmetic, sieve techniques, and Euler's totient.
01Basic Math & Parity
Arithmetic operations, parity reasoning, and divisibility rules.
3 easy2 medium
| Problem | Difficulty | Link |
|---|---|---|
| 4AWatermelon | easy | Solve |
| 231ATeam | easy | Solve |
| 1873BGood Kid | easy | Solve |
| 1900BLaura and Operations | medium | Solve |
| 1294CProduct of Three Numbers | medium | Solve |
02GCD & LCM
Greatest common divisor and least common multiple applications.
1 easy1 medium2 hard
| Problem | Difficulty | Link |
|---|---|---|
| 1850BTen Words of Wisdom | easy | Solve |
| 1881DDivide and Equalize | medium | Solve |
| 1900DSmall GCD | hard | Solve |
| 1033CPermutation Game | hard | Solve |
03Primes & Sieve of Eratosthenes
Primality testing, prime factorization, and sieve applications.
2 easy1 medium2 hard
| Problem | Difficulty | Link |
|---|---|---|
| 230BT-primes | easy | Solve |
| 1851CTiles Comeback | easy | Solve |
| 576AVasya and Petya's Game | medium | Solve |
| 1154GMinimum Possible LCM | hard | Solve |
| 735DTaxes | hard | Solve |
04Modular Arithmetic & Binary Exponentiation
Computing under modulo, fast exponentiation, modular inverse.
1 easy2 medium2 hard
| Problem | Difficulty | Link |
|---|---|---|
| 913AModular Exponentiation | easy | Solve |
| 1904CArray Game | medium | Solve |
| 630IParking Lot | medium | Solve |
| 1234CPipes | hard | Solve |
| 1837EPlayoff Fixing | hard | Solve |
05Euler's Totient Function
Count integers coprime to n; applications in modular inverse and order.
2 medium1 hard
| Problem | Difficulty | Link |
|---|---|---|
| 431Ck-Tree | medium | Solve |
| 776BSherlock and His Girlfriend | medium | Solve |
| 1295DSame GCDs | hard | Solve |
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