XY Sequence

greedy

Integer Moves

brute force, math

Neighbour Ordering

constructive algorithms, graphs

Equal LCM Subsets

data structures, math, number theory

Cycle Palindrome

constructive algorithms, graphs, math

Parametric MST

binary search, constructive algorithms, graphs, greedy, math, sortings

Equal Tree Sums

constructive algorithms, dfs and similar, math, trees

K-good

constructive algorithms, math, number theory

Make Equal With Mod

constructive algorithms, math, number theory, sortings

Subtract Operation

data structures, greedy, math, two pointers

Good Pairs

math, sortings

Three Minimums

combinatorics, constructive algorithms, divide and conquer, dp, fft, math

Snowy Mountain

data structures, dfs and similar, graphs, greedy, shortest paths, trees

Minimal String Xoration

bitmasks, data structures, divide and conquer, greedy, hashing, sortings, strings

Arithmetic Operations

brute force, data structures, graphs, math

Potion Brewing Class

dfs and similar, math, number theory, trees

Alice and the Cake

data structures, greedy, implementation, sortings

Prefix Removals

strings

Maximum Cake Tastiness

brute force, greedy, implementation, sortings

Tower Defense

binary search, brute force, data structures

Sum of Matchings

brute force, combinatorics, constructive algorithms, dfs and similar, graph matchings, greedy, math

Nearest Excluded Points

binary search, data structures, dfs and similar, graphs, shortest paths

Fault-tolerant Network

brute force, data structures, implementation

Prove Him Wrong

constructive algorithms, greedy

Playoff

implementation

Counting Shortcuts

data structures, dfs and similar, dp, graphs, shortest paths

Vitaly and Advanced Useless Algorithms

dp, greedy, implementation

Rescheduling the Exam

binary search, data structures, greedy, implementation, math, sortings

Twist the Permutation

brute force, constructive algorithms, implementation, math

Weight of the System of Nested Segments

greedy, hashing, implementation, sortings

DIV + MOD

math

Deletions of Two Adjacent Letters

implementation, strings

Game of Ball Passing

greedy, implementation

Game

implementation

Two Avenues

data structures, dfs and similar, graphs

Air Reform

data structures, dfs and similar, divide and conquer, dsu, graphs, implementation, trees

Serious Business

data structures, divide and conquer, dp, implementation, shortest paths

Tyler and Strings

combinatorics, data structures, implementation

Integral Array

brute force, constructive algorithms, data structures, math

Weird Sum

combinatorics, data structures, geometry, math, matrices, sortings

Madoka and Laziness

dp, greedy

Madoka and the Sixth-graders

data structures, dfs and similar, greedy

Madoka and the Best School in Russia

constructive algorithms, dp, math, number theory

Madoka and Childish Pranks

constructive algorithms, greedy

Madoka and the Elegant Gift

brute force, constructive algorithms, graphs, implementation

Madoka and Math Dad

implementation, math

Playing Around the Table

constructive algorithms, greedy, implementation

Power Board

brute force, dp, math, number theory

Weight the Tree

constructive algorithms, dfs and similar, dp, implementation, trees

Factorials and Powers of Two

bitmasks, brute force, constructive algorithms, dp, math

Quality vs Quantity

brute force, constructive algorithms, greedy, sortings, two pointers

Square Counting

math

Basis

combinatorics, fft, math, number theory

Expand the Path

brute force, combinatorics, data structures, implementation, math

Cross Coloring

data structures, implementation, math

Increase Subarray Sums

brute force, dp, greedy, implementation

Anti-Fibonacci Permutation

brute force, constructive algorithms, implementation

Doors and Keys

implementation

Power Walking

greedy

Hard Way

geometry

Covering Circle

geometry

Special Positions

combinatorics, divide and conquer, fft, math

Two Arrays

bitmasks, brute force, combinatorics, greedy, hashing, math, two pointers

Anonymity Is Important

binary search, brute force, data structures, dsu, greedy, sortings

Repetitions Decoding

constructive algorithms, implementation, sortings

Great Sequence

brute force, greedy, sortings

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Treasure Hunt

graphs, interactive

Two Posters

brute force, data structures, greedy, two pointers

Colorful Operations

brute force, data structures, implementation

Big Brush

constructive algorithms, data structures, greedy, implementation

Inversion Graph

data structures, dsu, graphs, math

Odd Swap Sort

data structures, math, sortings

Reverse

constructive algorithms, greedy, math

Minimize Inversions Number

data structures, greedy, math, sortings

Birthday

constructive algorithms, greedy, math

Towers

constructive algorithms, dfs and similar, dp, greedy, trees

Best Pair

binary search, brute force, implementation

Yet Another Minimization Problem

dp, greedy, math

Andrew and Stones

greedy, implementation

MEX and Array

brute force, dp, greedy, math

Sorting Parts

brute force, sortings

Closest Pair

data structures, greedy

Cars

2-sat, constructive algorithms, dfs and similar, dsu, graphs, greedy, sortings

Infinite Set

bitmasks, dp, math, matrices, number theory, strings

Differential Sorting

constructive algorithms, greedy

Avoid Local Maximums

greedy

Min Or Sum

bitmasks, greedy

Fibonacci Additions

brute force, data structures, hashing, implementation, math

Fair Share

constructive algorithms, data structures, dfs and similar, graph matchings, graphs

Finding Zero

constructive algorithms, interactive, math