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.

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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)
651	Codeforces 135D: Cycle
650	Codeforces 135C: Zero-One
649	Codeforces 135B: Rectangle and Square
648	Codeforces 135A: Replacement
647	Codeforces 134C: Swaps
646	Codeforces 134B: Pairs of Numbers
645	Codeforces 134A: Average Numbers
644	Codeforces 133B: Unary
643	Codeforces 133A: HQ9+
642	Codeforces 132E: Bits of merry old England
641	Codeforces 132D: Constants in the language of Shakespeare
640	Codeforces 132C: Logo Turtle
639	Codeforces 132B: Piet
638	Codeforces 132A: Turing Tape
637	Codeforces 131F: Present to Mom
636	Codeforces 131E: Yet Another Task with Queens
635	Codeforces 131D: Subway
634	Codeforces 131C: The World is a Theatre
633	Codeforces 131B: Opposites Attract
632	Codeforces 131A: cAPS lOCK
631	Codeforces 130J: Date calculation
630	Codeforces 130I: Array sorting
629	Codeforces 130H: Balanced brackets
628	Codeforces 130G: CAPS LOCK ON
627	Codeforces 130F: Prime factorization
626	Codeforces 130E: Tribonacci numbers
625	Codeforces 130D: Exponentiation
624	Codeforces 130C: Decimal sum
623	Codeforces 130B: Gnikool Ssalg
622	Codeforces 130A: Hexagonal numbers
621	Codeforces 129B: Students and Shoelaces
620	Codeforces 129A: Cookies
619	Codeforces 128E: Birthday
618	Codeforces 128D: Numbers
617	Codeforces 128C: Games with Rectangle
616	Codeforces 128B: String
615	Codeforces 128A: Statues
614	Codeforces 127B: Canvas Frames
613	Codeforces 127A: Wasted Time
612	Codeforces 126E: Pills
611	Codeforces 126D: Fibonacci Sums
610	Codeforces 126C: E-reader Display
609	Codeforces 126B: Password
608	Codeforces 126A: Hot Bath
607	Codeforces 125E: MST Company
606	Codeforces 125D: Two progressions
605	Codeforces 125C: Hobbits' Party
604	Codeforces 125B: Simple XML
603	Codeforces 125A: Measuring Lengths in Baden
602	Codeforces 124B: Permutations

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

651

Codeforces 135D: Cycle

650

Codeforces 135C: Zero-One

649

Codeforces 135B: Rectangle and Square

648

Codeforces 135A: Replacement

647

Codeforces 134C: Swaps

646