Surprise me!

divide and conquer, math, number theory, trees

Fake bullions

combinatorics, dfs and similar, dp, graphs, number theory

Coprime Subsequences

bitmasks, combinatorics, number theory

Mike and gcd problem

dp, greedy, number theory

k-Factorization

implementation, math, number theory

Colored Balls

greedy, math, number theory

Divide by Three

dp, greedy, math, number theory

The Monster

brute force, math, number theory

Anton and School - 2

combinatorics, dp, math, number theory

The Holmes Children

math, number theory

Sherlock and his girlfriend

constructive algorithms, number theory

Perfectionist Arkadiy

*special problem, number theory

Pens And Days Of Week

*special problem, binary search, number theory

Big Number and Remainder

*special problem, math, number theory

Test Data Generation

combinatorics, divide and conquer, dp, fft, math, number theory

Vulnerable Kerbals

constructive algorithms, dp, graphs, math, number theory

Barrels and boxes

brute force, combinatorics, math, number theory, probabilities

Mahmoud and a Triangle

constructive algorithms, geometry, greedy, math, number theory, sortings

Math, math everywhere

brute force, dp, math, meet-in-the-middle, number theory

Timofey and remoduling

brute force, implementation, math, number theory

k-th divisor

math, number theory

Geometrical Progression

brute force, math, number theory

Blown Garland

brute force, implementation, number theory

Bash Plays with Functions

brute force, combinatorics, dp, number theory

Bash's Big Day

greedy, math, number theory

Long number

expression parsing, math, number theory

PolandBall and Many Other Balls

combinatorics, divide and conquer, dp, fft, math, number theory

PolandBall and Hypothesis

brute force, graphs, math, number theory

Bachgold Problem

greedy, implementation, math, number theory

Vladik and fractions

brute force, constructive algorithms, math, number theory

Arpa’s obvious problem and Mehrdad’s terrible solution

brute force, math, number theory

Arpa’s hard exam and Mehrdad’s naive cheat

implementation, math, number theory

Taxes

math, number theory

Urbanization

greedy, number theory, sortings

Video Cards

brute force, data structures, implementation, math, number theory

Xor-matic Number of the Graph

bitmasks, graphs, math, number theory, trees

Ray Tracing

greedy, hashing, implementation, math, number theory, sortings

Cyclic Cipher

chinese remainder theorem, data structures, implementation, number theory, two pointers

Festival Organization

combinatorics, math, number theory

ZS and The Birthday Paradox

math, number theory, probabilities

Two Arithmetic Progressions

math, number theory

Pythagorean Triples

math, number theory

Mishka and Divisors

dp, number theory

Coprime Permutation

combinatorics, number theory

Couple Cover

brute force, dp, number theory

Remainders Game

chinese remainder theorem, math, number theory

Alyona and Numbers

constructive algorithms, math, number theory

Iterated Linear Function

math, number theory

Joty and Chocolate

implementation, math, number theory

Ultimate Weirdness of an Array

data structures, number theory

Four Divisors

data structures, dp, math, number theory, sortings, two pointers

Simple Subset

constructive algorithms, greedy, number theory

Complicated GCD

math, number theory

Co-prime Array

greedy, implementation, math, number theory

Fence Divercity

combinatorics, dp, number theory

Move by Prime

combinatorics, math, number theory

Cowslip Collections

combinatorics, math, number theory

Yash And Trees

bitmasks, data structures, dfs and similar, math, number theory

A Trivial Problem

brute force, constructive algorithms, math, number theory

Ebony and Ivory

brute force, math, number theory

Longest Subsequence

brute force, math, number theory

Indivisibility

math, number theory

Divisibility

math, number theory

Again Twenty Five!

number theory

Block Towers

brute force, greedy, math, number theory

Array GCD

dp, greedy, number theory

Wet Shark and Flowers

combinatorics, math, number theory, probabilities

Sum of Remainders

implementation, math, number theory

Multipliers

math, number theory

Moodular Arithmetic

combinatorics, dfs and similar, dsu, math, number theory

REQ

data structures, number theory

Present for Vitalik the Philatelist

combinatorics, math, number theory

Alice, Bob, Oranges and Apples

number theory

Dima and Lisa

brute force, math, number theory

Number of Binominal Coefficients

dp, math, number theory

Superior Periodic Subarrays

number theory

GCD Table

constructive algorithms, greedy, number theory

Multiplication Table

implementation, number theory

Vasya and Petya's Game

math, number theory

Bots

combinatorics, dp, math, number theory

Bear and Poker

implementation, math, number theory

Primes or Palindromes?

brute force, implementation, math, number theory

Clique in the Divisibility Graph

dp, math, number theory

Gerald and Giant Chess

combinatorics, dp, math, number theory

Vanya and Scales

brute force, dp, greedy, math, meet-in-the-middle, number theory

GukiZ and Binary Operations

combinatorics, implementation, math, matrices, number theory

Mike and Foam

bitmasks, combinatorics, dp, math, number theory

Soldier and Number Game

constructive algorithms, dp, math, number theory

Superhero's Job

dfs and similar, dp, hashing, math, number theory

Pluses everywhere

combinatorics, dp, math, number theory

A and B and Team Training

greedy, implementation, math, number theory

Drazil and His Happy Friends

math, number theory

Drazil and His Happy Friends

brute force, dsu, meet-in-the-middle, number theory

New Year Running

number theory, trees

Traffic Jams in the Land

data structures, dp, number theory

Array and Operations

flows, graph matchings, number theory

Modular Equations

math, number theory

Chocolate

brute force, dfs and similar, math, meet-in-the-middle, number theory

Hacking Cypher

brute force, math, number theory, strings

Prefix Product Sequence

constructive algorithms, math, number theory