Jumping Jack

math

Cinema Cashier

dp, implementation

How many trees?

combinatorics, divide and conquer, dp

Obsession with Robots

constructive algorithms, graphs, implementation

Line

math, number theory

Memory Manager

implementation

Exposition

binary search, data structures, dsu, trees, two pointers

Longest Regular Bracket Sequence

constructive algorithms, data structures, dp, greedy, sortings, strings

Mysterious Present

dp, sortings

Registration System

data structures, hashing, implementation

Tic-tac-toe

brute force, games, implementation

Lorry

greedy, sortings

Winner

hashing, implementation

Spreadsheet

implementation, math