Starlight: List of Problems

Over 20,000 problems available. AMC 8/10/12 and AIME problems from 2010-2023; USAJMO/USAMO problems from 2002-2023 available. USACO problems from 2014 to 2023 (all divisions). Codeforces, AtCoder, DMOJ problems are added daily around 04:00 AM UTC, which may cause disruptions.

Need help searching? Click for format/examples of problems

AMC 8: [year] AMC 8 Problem #, Ex: 2013 AMC 8 Problem 1
AMC 10: [year] AMC 10A Problem # OR [year] AMC 10B Problem #, Ex: 2015 AMC 10A Problem 16
AMC 12: [year] AMC 12A Problem # OR [year] AMC 12B Problem #, Ex: 2021 AMC 12B Problem 25
AIME: [year] AIME I Problem # OR [year] AIME II Problem #, Ex: 2013 AIME I Problem 8
USAJMO/USAMO: [year] USAJMO/USAMO Problem #, Ex: 2023 USAJMO Problem 1
Codeforces: Codeforces [contest id (e.g. 101)][problem id (e.g. A, B, C)]: [Codeforces problem name], Ex: Codeforces 1336F: Journey
AtCoder: AtCoder [contest id (e.g. ABC314, ARC164, ZONE2021)]: [problem id (A, B, C)]. [Problem name], Ex: AtCoder ZONE2021: E. Sneaking
DMOJ: DMOJ [contest name (if applicable)] [problem number (e.g. P1)] - [Problem name], Ex: DMOJ Yet Another Contest 3 P1 - Shell Swap Scam
USACO: [year] [contest month (e.g. January, US Open)], [division (e.g. Gold)]: [Problem name], Ex: USACO 2023 US Open Contest, Bronze: Rotate and Shift

ID	Problem Name (click to add insights/hints, view summary of insights/hints and similar problems)
18151	DMOJ IOI '21 P4 - Mutating DNA
18150	DMOJ IOI '21 P3 - Fountain Parks
18149	DMOJ IOI '21 P2 - Keys
18148	DMOJ IOI '21 P1 - Distributing Candies
18147	DMOJ IOI '20 P6 - Stations
18146	DMOJ IOI '20 P5 - Counting Mushrooms
18145	DMOJ IOI '20 P4 - Packing Biscuits
18144	DMOJ IOI '20 P3 - Carnival Tickets
18143	DMOJ IOI '20 P2 - Connecting Supertrees
18142	DMOJ IOI '20 P1 - Comparing Plants
18141	DMOJ IOI '19 P6 - Sky Walking
18140	DMOJ IOI '19 P5 - Vision Program
18139	DMOJ IOI '19 P4 - Broken Line
18138	DMOJ IOI '19 P3 - Rectangles
18137	DMOJ IOI '19 P2 - Split the Attractions
18136	DMOJ IOI '19 P1 - Arranging Shoes
18135	DMOJ IOI '18 P6 - Meetings
18134	DMOJ IOI '18 P5 - Highway Tolls
18133	DMOJ IOI '18 P4 - Mechanical Doll
18132	DMOJ IOI '18 P3 - Werewolf
18131	DMOJ IOI '18 P2 - Seats
18130	DMOJ IOI '18 P1 - Combo
18129	DMOJ IOI '17 P6 - Ancient Books
18128	DMOJ IOI '17 P5 - Simurgh
18127	DMOJ IOI '17 P4 - The Big Prize
18126	DMOJ IOI '17 P3 - Toy Train
18125	DMOJ IOI '17 P2 - Wiring
18124	DMOJ IOI '17 P1 - Nowruz
18123	DMOJ IOI '16 P6 - Aliens (Standard I/O)
18122	DMOJ IOI '16 P6 - Aliens
18121	DMOJ IOI '16 P5 - Unscrambling a Messy Bug
18120	DMOJ IOI '16 P4 - Paint by Numbers (Standard I/O)
18119	DMOJ IOI '16 P4 - Paint by Numbers
18118	DMOJ IOI '16 P3 - Shortcut (Standard I/O)
18117	DMOJ IOI '16 P3 - Shortcut
18116	DMOJ IOI '16 P2 - Roller Coaster Railroad (Standard I/O)
18115	DMOJ IOI '16 P2 - Roller Coaster Railroad
18114	DMOJ IOI '16 P1 - Detecting Molecules (Standard I/O)
18113	DMOJ IOI '16 P1 - Detecting Molecules
18112	DMOJ IOI '15 P6 - Towns
18111	DMOJ IOI '15 P5 - Sorting (Standard I/O)
18110	DMOJ IOI '15 P5 - Sorting
18109	DMOJ IOI '15 P4 - Horses (Standard I/O)
18108	DMOJ IOI '15 P4 - Horses
18107	DMOJ IOI '15 P3 - Teams (Standard I/O)
18106	DMOJ IOI '15 P3 - Teams
18105	DMOJ IOI '15 P2 - Scales
18104	DMOJ IOI '15 P1 - Boxes with Souvenirs (Standard I/O)
18103	DMOJ IOI '15 P1 - Boxes with Souvenirs
18102	DMOJ IOI '14 Practice Task 3 - Tile

Problem Name (click to add insights/hints, view summary of insights/hints and similar problems)

18151

DMOJ IOI '21 P4 - Mutating DNA

18150

DMOJ IOI '21 P3 - Fountain Parks

18149

DMOJ IOI '21 P2 - Keys

18148

DMOJ IOI '21 P1 - Distributing Candies

18147

DMOJ IOI '20 P6 - Stations

18146