Heidi Learns Hashing (Hard)

fft, math, number theory

Triple

fft, math

Pavel and Triangles

brute force, dp, fft, greedy, ternary search

Radix sum

fft, math, number theory

Lucky Tickets

divide and conquer, dp, fft

Epic Convolution

chinese remainder theorem, fft, math, number theory

Boolean Computer

bitmasks, brute force, fft, math

Covered Points

fft, geometry, number theory

Tree

fft, graphs, trees

Nikita and Order Statistics

chinese remainder theorem, fft, math

Perfect Encoding

fft, math

K Paths

combinatorics, data structures, dp, fft, math

Lightsabers (hard)

fft

Bandit Blues

combinatorics, dp, fft, math

Yet Another String Matching Problem

fft, math

Perpetual Subtraction

fft, math, matrices

Sum the Fibonacci

bitmasks, divide and conquer, dp, fft, math

Cyclic Cipher

fft, math

Random Elections

bitmasks, brute force, divide and conquer, fft, math

Days of Floral Colours

combinatorics, divide and conquer, dp, fft, math

Rusty String

fft, math, strings

Test Data Generation

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

PolandBall and Many Other Balls

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

Dasha and cyclic table

bitmasks, brute force, fft, strings, trees

Complete the Permutations

combinatorics, fft, graphs, math

Binary Table

bitmasks, brute force, divide and conquer, dp, fft, math

Thief in a Shop

divide and conquer, dp, fft, math

Transforming Sequence

combinatorics, dp, fft, math

Kyoya and Train

dp, fft, graphs, math, probabilities

Fuzzy Search

bitmasks, brute force, fft

Design Tutorial: Increase the Constraints

bitmasks, data structures, fft

The Child and Binary Tree

combinatorics, divide and conquer, fft, number theory

Painting Square

dp, fft

Ladies' Shop

constructive algorithms, fft, math