Card Pairing

dp, greedy, implementation

Unique Array

binary search, data structures, divide and conquer, dp, greedy

Minimizing the Sum

dp, implementation

Again Counting Arrays (Hard Version)

combinatorics, dp

Again Counting Arrays (Easy Version)

combinatorics, dp, fft, math

Fenwick Tree

brute force, combinatorics, data structures, dp, math, matrices, trees

Carousel of Combinations

brute force, combinatorics, dp, math, number theory

A BIT of an Inequality

bitmasks, brute force, dp, math

How Does the Rook Move?

combinatorics, dp, math

Nene and the Mex Operator

bitmasks, brute force, constructive algorithms, divide and conquer, dp, greedy, implementation, math

The Most Reckless Defense

bitmasks, brute force, constructive algorithms, dp, flows, graph matchings, shortest paths

GCD on a grid

brute force, dfs and similar, dp, implementation, math, number theory

Unfair Game

dp, games, greedy, math, schedules

Unique Strings

combinatorics, dp, math

Colored Balls

combinatorics, dp, math, sortings

Thanos Snap

binary search, dp, games, greedy, trees

Shuffling Songs

bitmasks, dfs and similar, dp, graphs, hashing, implementation, strings

Product of Binary Decimals

brute force, dp, implementation, number theory

Annual Ants' Gathering

dfs and similar, dp, greedy, trees

Grove

brute force, dfs and similar, dp, geometry, probabilities

Arrow Path

brute force, constructive algorithms, dfs and similar, dp, graphs, shortest paths

Array Fix

brute force, dp, greedy, implementation

Nobody is needed

2-sat, data structures, dfs and similar, dp

Girl Permutation

combinatorics, dp, math, number theory

Tree Cutting

binary search, dp, greedy, implementation, trees

Maximum Sum

dp, greedy, math

Seraphim the Owl

dp, greedy

Minimum Hamming Distance

dp

Counting Is Fun (Hard Version)

combinatorics, dp

Counting Is Fun (Easy Version)

brute force, combinatorics, dp, math

Farmer John's Favorite Intern

data structures, dp, flows, trees

Bessie and Cards

combinatorics, dp, math

Learning to Paint

binary search, data structures, dfs and similar, dp, greedy, implementation, sortings

Rudolf and k Bridges

binary search, data structures, dp, two pointers

Rudolf and the Ball Game

dfs and similar, dp, implementation

Rudolf and the Ugly String

dp, greedy, strings

Rudolf and 121

brute force, dp, greedy, math

Big Persimmon

*special problem, dp, games

Draw Polygon Lines

*special problem, constructive algorithms, dp, geometry, interactive

Binary Path

dp, greedy, implementation

Messenger in MAC

binary search, brute force, constructive algorithms, data structures, dp, greedy, sortings

Yet Another Coin Problem

brute force, dp, greedy, math

Turtle Mission: Robot and the Earthquake

dfs and similar, dp, graphs, shortest paths

Feed Cats

data structures, dp, sortings

Thorns and Coins

dp, greedy, implementation

Prefix Max Set Counting

data structures, dp, trees

2..3...4.... Wonderful! Wonderful!

combinatorics, dp, math

Sum over all Substrings (Hard Version)

bitmasks, divide and conquer, dp, dsu, greedy, implementation, strings

Sum over all Substrings (Easy Version)

brute force, dp, greedy, strings

Sasha and the Happy Tree Cutting

bitmasks, brute force, dfs and similar, dp, graphs, greedy, math, trees

Sasha and a Walk in the City

combinatorics, dp, math, trees

Modular Sequence

brute force, constructive algorithms, dp, graphs, greedy, math, number theory

Paint Charges

data structures, dp, greedy, math

Find the Different Ones!

binary search, brute force, data structures, dp, dsu, greedy, two pointers

Vlad and Trouble at MIT

dfs and similar, dp, flows, graphs, greedy, implementation, trees

Vlad and Avoiding X

bitmasks, brute force, dfs and similar, dp, implementation

Vlad and an Odd Ordering

binary search, bitmasks, data structures, dp, implementation, math, number theory

Vlad and a Sum of Sum of Digits

dp, implementation

Good Trip

combinatorics, dp, math, probabilities

Anti-Proxy Attendance

constructive algorithms, dp, interactive, ternary search

Balanced Subsequences

combinatorics, dp, math

Did We Get Everything Covered?

constructive algorithms, dp, greedy, shortest paths, strings

Count Paths

data structures, dfs and similar, dp, dsu, graphs, trees

Monsters Attack!

dp, greedy, implementation

Replace on Segment

dp, graph matchings

Mischievous Shooter

brute force, data structures, divide and conquer, dp, implementation

Sum of Progression

brute force, data structures, dp, implementation, math

Counting Binary Strings

combinatorics, dp, math

Wine Factory (Hard Version)

data structures, dp, flows, greedy, matrices

Counting Prefixes

combinatorics, constructive algorithms, dp, implementation, math

Grouping Increases

data structures, dp, greedy

Blocking Elements

binary search, data structures, dp, implementation, two pointers

Construct Tree

bitmasks, constructive algorithms, dp, trees

Yet Another Inversions Problem

combinatorics, data structures, dp, implementation, math, number theory

Erase First or Second Letter

brute force, combinatorics, data structures, dp, strings

Matrix Rank (Hard Version)

combinatorics, dp, math, matrices, string suffix structures

Matrix Rank (Easy Version)

brute force, combinatorics, dp, math, matrices

Optimizations From Chelsu

divide and conquer, dp, number theory, trees

Light Bulbs (Hard Version)

combinatorics, data structures, dfs and similar, dp, graphs, hashing

Light Bulbs (Easy Version)

brute force, combinatorics, dfs and similar, dp, dsu, graphs, math, trees

Programming Competition

dfs and similar, dp, graph matchings, greedy, trees

Three Activities

brute force, dp, greedy, implementation, sortings

Array Collapse

data structures, divide and conquer, dp, trees

Kim's Quest

bitmasks, combinatorics, dp

Inverse Problem

*special problem, combinatorics, dp

Maximum Sum Subarrays

*special problem, dp

Short Permutation Problem

combinatorics, dp, fft, math

Small Permutation Problem (Hard Version)

combinatorics, dp, math

Small Permutation Problem (Easy Version)

brute force, combinatorics, dp, math

Count BFS Graph

combinatorics, dp

Twin Friends

combinatorics, dp

Merge Not Sort

constructive algorithms, dp

One-X

combinatorics, dfs and similar, dp, math, trees

Collecting Game

binary search, dp, greedy, sortings, two pointers

Maximum And Queries (hard version)

bitmasks, divide and conquer, dp, greedy

Robot Queries

binary search, data structures, dp, implementation

Compressed Tree

dfs and similar, dp, graphs, greedy, sortings, trees

Yet Another Monster Fight

binary search, dp, greedy, implementation, math

Transitive Graph

dfs and similar, dp, dsu, graphs, implementation

Small GCD

bitmasks, brute force, dp, math, number theory