Summer Oenothera Exhibition

data structures

Half-sum

brute force, divide and conquer, greedy

Swiper, no swiping!

graphs, implementation

Stations

data structures

Hard Cut

constructive algorithms, dfs and similar, divide and conquer, math

Island Puzzle

dfs and similar, dsu, graphs, trees

Ember and Storm's Tree Game

combinatorics, dp, games, trees

Phoenix and Diamonds

binary search, data structures, sortings

Happy Cactus

dp

Radix sum

fft, math, number theory

Fedya the Potter

binary search, implementation, math, number theory

Caramel Clouds

data structures, dp, sortings

Tree

fft, graphs, trees

Days of Floral Colours

combinatorics, divide and conquer, dp, fft, math

Stairs

combinatorics, divide and conquer, dp, fft, math

Test Data Generation

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

Iqea

data structures, dfs and similar, divide and conquer, dsu, shortest paths, trees

The Riddle of the Sphinx

binary search, data structures, data structures, interactive

Number Discovery

math

Recover a functional graph

graph matchings

Arpa’s abnormal DNA and Mehrdad’s deep interest

data structures, string suffix structures

Minimums or Medians

Two Sorts

binary search, dfs and similar, math, meet-in-the-middle

Doremy's Paint 2

data structures

Mini Metro

dp

Rivalries

constructive algorithms, data structures, greedy

Passports

dp, implementation

Koxia and Bracket

divide and conquer, fft, math

Treasure Hunt

data structures, divide and conquer, two pointers

So Mean

interactive, math

Strange device

binary search, interactive, math, trees

Turing's Award

data structures, dp

Fake bullions

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

Rap God

data structures, dfs and similar, hashing, strings, trees

Balls and Pockets

data structures

Multiple of Three Cycles

combinatorics, data structures, dp, dsu, math

Differentiating Games

games, interactive

Don't Exceed

math, probabilities

Organizing a Music Festival

dfs and similar, math

Beauty of a Permutation

constructive algorithms, math

Upside Down

data structures, string suffix structures, strings, trees

Pisces

data structures, flows, trees

Minimum Segments

constructive algorithms

Harder Satisfiability

2-sat, dfs and similar, graphs

Red-Blue Graph

dp, graphs, math, matrices, meet-in-the-middle

Yet Yet Another Permutation Problem

divide and conquer, fft, math

Mateusz and an Infinite Sequence

bitmasks, brute force, dp, strings

Shady Lady

geometry, math

Long number

expression parsing, math, number theory

Tokitsukaze and Powers

number theory, probabilities

Negative Time Summation

constructive algorithms

Cyclic Hamming (Easy Version)

brute force, divide and conquer, dp, fft, math, number theory

Bad Cryptography

math, number theory

Railway Construction

brute force, constructive algorithms, data structures, graphs, shortest paths

Lada Malina

data structures, geometry

Intergalactic Sliding Puzzle

combinatorics, constructive algorithms, math

Geolocation

geometry

Zero-XOR Array

*special problem, dp

Kuroni and Antihype

bitmasks, brute force, dp, dsu, graphs

Beautiful Fibonacci Problem

constructive algorithms, number theory

Replace

binary search, data structures

Intervals of Intervals

binary search, data structures, two pointers

Beautiful fountains rows

data structures

Density of subarrays

dp, math

Cactus Revenge

constructive algorithms

Chip Game

games

Making Shapes

dp

Cupboards Jumps

dp

Rin and The Unknown Flower

constructive algorithms, greedy, interactive, math

Minimize Inversions Number

data structures, greedy, math, sortings

Nora's Toy Boxes

bitmasks, combinatorics, dp

Chiori and Doll Picking (hard version)

bitmasks, brute force, combinatorics, math

My Beautiful Madness

data structures, trees

Modest Substrings

dp, strings

XOR-ranges

dp, greedy

Jumping Through the Array

binary search, data structures, graphs, two pointers

Range Diameter Sum

data structures, trees

Holy Diver

data structures

Zigzag Game

games, interactive

Just Add an Edge

dfs and similar, dp, graphs

Hopping Around the Array

data structures, dp

Communism

bitmasks, dp, trees

JYPnation

graphs

Xor on Figures

constructive algorithms, fft, math

Bully Sort

data structures, math

The Fair Nut's getting crazy

data structures, implementation

Forest Fires

math

Breadboard Capacity (hard version)

Ж-function

string suffix structures, strings

Speckled Band

data structures, divide and conquer, hashing, string suffix structures, strings

Cheat and Win

bitmasks, data structures, games, trees

OH NO1 (-2-3-4)

constructive algorithms, graphs, math

Become Big For Me

combinatorics, constructive algorithms, greedy, math, number theory

Phoenix and Bits

bitmasks, brute force, data structures, sortings

Stock Exchange

binary search, flows, graphs

Old Mobile

combinatorics, dp, probabilities

Journey

data structures, divide and conquer, graphs, trees

Flow Control

data structures, dsu, implementation

Euler tour

constructive algorithms, trees

New Year and Snowy Grid

dfs and similar, dsu, graphs, interactive