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)
2651	Codeforces 624B: Making a String
2650	Codeforces 624A: Save Luke
2649	Codeforces 623E: Transforming Sequence
2648	Codeforces 623D: Birthday
2647	Codeforces 623C: Electric Charges
2646	Codeforces 623B: Array GCD
2645	Codeforces 623A: Graph and String
2644	Codeforces 622F: The Sum of the k-th Powers
2643	Codeforces 622E: Ants in Leaves
2642	Codeforces 622D: Optimal Number Permutation
2641	Codeforces 622C: Not Equal on a Segment
2640	Codeforces 622B: The Time
2639	Codeforces 622A: Infinite Sequence
2638	Codeforces 621E: Wet Shark and Blocks
2637	Codeforces 621D: Rat Kwesh and Cheese
2636	Codeforces 621C: Wet Shark and Flowers
2635	Codeforces 621B: Wet Shark and Bishops
2634	Codeforces 621A: Wet Shark and Odd and Even
2633	Codeforces 620F: Xors on Segments
2632	Codeforces 620E: New Year Tree
2631	Codeforces 620D: Professor GukiZ and Two Arrays
2630	Codeforces 620C: Pearls in a Row
2629	Codeforces 620B: Grandfather Dovlet’s calculator
2628	Codeforces 620A: Professor GukiZ's Robot
2627	Codeforces 618G: Combining Slimes
2626	Codeforces 618F: Double Knapsack
2625	Codeforces 618E: Robot Arm
2624	Codeforces 618D: Hamiltonian Spanning Tree
2623	Codeforces 618C: Constellation
2622	Codeforces 618B: Guess the Permutation
2621	Codeforces 618A: Slime Combining
2620	Codeforces 617E: XOR and Favorite Number
2619	Codeforces 617D: Polyline
2618	Codeforces 617C: Watering Flowers
2617	Codeforces 617B: Chocolate
2616	Codeforces 617A: Elephant
2615	Codeforces 616F: Expensive Strings
2614	Codeforces 616E: Sum of Remainders
2613	Codeforces 616D: Longest k-Good Segment
2612	Codeforces 616C: The Labyrinth
2611	Codeforces 616B: Dinner with Emma
2610	Codeforces 616A: Comparing Two Long Integers
2609	Codeforces 615E: Hexagons
2608	Codeforces 615D: Multipliers
2607	Codeforces 615C: Running Track
2606	Codeforces 615B: Longtail Hedgehog
2605	Codeforces 615A: Bulbs
2604	Codeforces 614B: Gena's Code
2603	Codeforces 614A: Link/Cut Tree
2602	Codeforces 613E: Puzzle Lover

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

2651

Codeforces 624B: Making a String

2650

Codeforces 624A: Save Luke

2649

Codeforces 623E: Transforming Sequence

2648

Codeforces 623D: Birthday

2647

Codeforces 623C: Electric Charges

2646