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)
13851	AtCoder PAST201912-OPEN: E. Restore
13850	AtCoder PAST201912-OPEN: D. Duplicated?
13849	AtCoder PAST201912-OPEN: C. The Third
13848	AtCoder PAST201912-OPEN: B. Up and Down
13847	AtCoder PAST201912-OPEN: A. Is It a Number?
13846	AtCoder PANASONIC2020: F. Fractal Shortest Path
13845	AtCoder PANASONIC2020: E. Three Substrings
13844	AtCoder PANASONIC2020: D. String Equivalence
13843	AtCoder PANASONIC2020: C. Sqrt Inequality
13842	AtCoder PANASONIC2020: B. Bishop
13841	AtCoder PANASONIC2020: A. Kth Term
13840	AtCoder PAKENCAMP-2022-DAY3: L. X and Xor
13839	AtCoder PAKENCAMP-2022-DAY3: K. Inner Product
13838	AtCoder PAKENCAMP-2022-DAY3: J. Balanced Permutation
13837	AtCoder PAKENCAMP-2022-DAY3: I. Prefix Or
13836	AtCoder PAKENCAMP-2022-DAY3: H. Exactly K Square Numbers
13835	AtCoder PAKENCAMP-2022-DAY3: G. 4x4
13834	AtCoder PAKENCAMP-2022-DAY3: F. Cycle and Xor
13833	AtCoder PAKENCAMP-2022-DAY3: E. Output-only
13832	AtCoder PAKENCAMP-2022-DAY3: D. Yet Another Balls and Boxes Problem
13831	AtCoder PAKENCAMP-2022-DAY3: C. Permutation of Length 26
13830	AtCoder PAKENCAMP-2022-DAY3: B. Chmax
13829	AtCoder PAKENCAMP-2022-DAY3: A. Moving Piece
13828	AtCoder PAKENCAMP-2022-DAY2: H. Habatu
13827	AtCoder PAKENCAMP-2022-DAY2: G. Worst Town
13826	AtCoder PAKENCAMP-2022-DAY2: F. Farthest
13825	AtCoder PAKENCAMP-2022-DAY2: E. Harmony
13824	AtCoder PAKENCAMP-2022-DAY2: D. Binary Strings
13823	AtCoder PAKENCAMP-2022-DAY2: C. Collaboration
13822	AtCoder PAKENCAMP-2022-DAY2: B. Grades
13821	AtCoder PAKENCAMP-2022-DAY2: A. Venues
13820	AtCoder PAKENCAMP-2022-DAY1: O. Paken Land
13819	AtCoder PAKENCAMP-2022-DAY1: N. Paken Machine
13818	AtCoder PAKENCAMP-2022-DAY1: M. 01 Tree
13817	AtCoder PAKENCAMP-2022-DAY1: L. Mex on Blackboard 2
13816	AtCoder PAKENCAMP-2022-DAY1: K. Beautifulness
13815	AtCoder PAKENCAMP-2022-DAY1: J. An Unusual King in Paken Kingdom
13814	AtCoder PAKENCAMP-2022-DAY1: I. Forgotten Sequence
13813	AtCoder PAKENCAMP-2022-DAY1: H. Attack Survival
13812	AtCoder PAKENCAMP-2022-DAY1: G. Ancestor Query
13811	AtCoder PAKENCAMP-2022-DAY1: F. Events Scheduling
13810	AtCoder PAKENCAMP-2022-DAY1: E. Boombox
13809	AtCoder PAKENCAMP-2022-DAY1: D. Social Distance 3
13808	AtCoder PAKENCAMP-2022-DAY1: C. Let's Make a Palindrome
13807	AtCoder PAKENCAMP-2022-DAY1: B. Power Strip
13806	AtCoder PAKENCAMP-2022-DAY1: A. Rook
13805	AtCoder PAKENCAMP-2021-DAY3: H. パ研王国と貨物輸送
13804	AtCoder PAKENCAMP-2021-DAY3: G. 旅人計画問題3
13803	AtCoder PAKENCAMP-2021-DAY3: F. ワープ
13802	AtCoder PAKENCAMP-2021-DAY3: E. お菓子

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

13851

AtCoder PAST201912-OPEN: E. Restore

13850

AtCoder PAST201912-OPEN: D. Duplicated?

13849

AtCoder PAST201912-OPEN: C. The Third

13848

AtCoder PAST201912-OPEN: B. Up and Down

13847

AtCoder PAST201912-OPEN: A. Is It a Number?

13846