Problems

Pick a problem, code in the editor, and watch the judge run real test cases. The archive is open to browse

Under construction

Still being built. Things may change

Total results29,447 problems

Zombies Arrive Before My Discharge
Medium5
Brute force, Simulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mountains
Medium5
Array, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Experimental Charges
Medium5
Union-find, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
How Many Tests
Medium5
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Different digits
Medium5
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Retwinting twinter
Medium5
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Typing Trouble
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Birthday
Medium5
Implementation, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Stars on Shoulder Boards
Medium5
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chess
Medium5
Greedy, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Merlin
Medium5
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Olympiad Registration
Medium5
Hash map, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Disease
Medium5
Implementation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mysterious Equation
Medium5
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Half
Medium5
Implementation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Time Travel
Medium5
Tree, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Configuration File
Medium5
Stack, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Barbells
Medium5
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Simple Sequence of Digits
Medium5
Greedy, Stack+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bursting the Balloons
Medium5
Math, Greedy+2
No attempts yet
Time limit
0.25s
Memory limit
512 MB
Judgeable
Diet
Medium5
Brute force, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Connecting Rods in 3D
Medium5
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Do You Have a Problem with Insung??
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Chocolate
Medium5
Implementation, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Necklace
Medium5
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Unified State Exam
Medium5
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Phone Numbers
Medium5
String, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Secure Connection
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cycle Game
Medium5
Union-find, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Magician Shark and Fireball
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Monomino Domino 2
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Coins
Medium5
Bit manipulation, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Energy Drink
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Balance of Boxes
Medium5
Array, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Claire and Potions
Medium5
Graph, Topological sort+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Y-sequence
Medium5
Array, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Metroidvania Extreme
Medium5
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
There Is a Convenience Store Below My House
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hoseok, the Patient Domino Artisan
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hosuk Fell into String Hell
Medium5
Dynamic programming, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Alley Boss Hoseok - Feasibility
Medium5
Binary search, Graph+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Two Buildings
Medium5
Two pointers, Greedy
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Alley Boss Hoseok - Efficiency 1
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Selecting Numbers
Medium5
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Shortened Form
Medium5
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Patkice
Medium5
Graph, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Game Developer Youngwoo
Medium5
Simulation, Brute force+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Luggage
Medium5
Math, Number theory+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Easy Compare-and-Set
Medium5
Greedy, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Integer Square
Medium5
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pyramid
Medium5
Simulation, Implementation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Consulting
Medium5
Greedy, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mint Choco
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Thanos
Medium5
Greedy, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
CPU Benchmarking
Medium5
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Aquarium
Medium5
Greedy, Simulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Matrix Encryption
Medium5
Matrix, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lost in Space
Medium5
Array, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Blind Walk
Medium5
DFS, Graph
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The Comeback King (Easy)
Medium5
Simulation, Sorting
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Arrow Maze (Hard)
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Elevator
Medium5
Sorting, Simulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
ZOAC 3
Medium5
Dynamic programming, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Badminton Tournament
Medium5
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Interval Covering
Medium5
Dynamic programming, Intervals+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Campus
Medium5
Math, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Knight's Shield
Medium5
Geometry, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sticky Tape
Medium5
Dynamic programming, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Three Sons
Medium5
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Range Sum Query K
Medium5
Prefix sum, Array
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Permutations on the Road: Alice
Medium5
Array, Combinatorics+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Vaccination Against Corona
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Comic Binge
Medium5
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Easy Measurements
Medium5
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jumping Jack
Medium5
Binary search, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Efficient Data Structure
Medium5
Segment tree, Dynamic programming
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Brewing Tea
Medium5
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Björne's Storehouse
Medium5
Greedy, Intervals
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Renovation
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Multationer
Medium5
Brute force, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Robot Competition
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Meal Order
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Giant
Medium5
Geometry, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Moving Boxes
Medium5
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fluoride Dentist
Medium5
Array, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Computer Distribution
Medium5
Dynamic programming, Binary search
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
IOI Selection
Medium5
Sorting, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Snowball Fight 2
Medium5
Greedy, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Belarus
Medium5
Greedy, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Nangijala
Medium5
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
QWERTY Keyboard
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Social Distancing
Medium5
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
That Kind of Relationship
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
4.242s
Memory limit
1042 MB
Judgeable
I Hate Overlaps
Medium5
Sliding window, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tree Trunk and Branches
Medium5
Tree, DFS+2
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Degree Bounded Minimum Spanning Tree
Medium5
Backtracking, Minimum spanning tree+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Tteokguk
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Attacked City
Medium5
Simulation, Implementation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Artist Mimi
Medium5
Brute force, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Yua and the Gomduri Car
Medium5
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Zombies Arrive Before My DischargeGiven zombies on a road with health values and three limited firearms, decide whether Kilo can kill or stop every zombie before the one 1 m from the post reaches it.	Medium5	Brute forceSimulation	No attempts yet	2s	1024 MB	Judgeable
MountainsCount triples x < y < z where the middle mountain y is strictly taller than both mountain x and mountain z.	Medium5	ArrayCombinatorics+2	No attempts yet	2s	256 MB	Judgeable
Experimental ChargesParticles carry unknown plus or minus charges; process attract/repel observations online and answer whether a queried pair must attract, must repel, or is unconstrained.	Medium5	Union-findGraph+2	No attempts yet	2s	512 MB	Judgeable
How Many TestsGiven some surviving file names (equal length, digits only), find the minimum and maximum possible original test count n consistent with the zero-padding naming rule.	Medium5	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
Different digitsGiven n up to 10^18, find the smallest integer strictly greater than n whose decimal digits have no two adjacent equal digits.	Medium5	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
Retwinting twinterGiven a chain of twints with (i/n) suffixes, repack the words into the fewest twints of at most 280 characters and renumber them.	Medium5	GreedyString+1	No attempts yet	1s	512 MB	Judgeable
Typing TroubleDecide whether t can be produced from s when stray Home presses split s into blocks that are each placed at the front of the line.	Medium5	Dynamic programmingString+1	No attempts yet	1s	512 MB	Judgeable
BirthdayGiven a list of candidate dates and a three-line dialogue between the day-knower and month-knower, determine the unique birthday consistent with all statements.	Medium5	ImplementationSimulation+2	No attempts yet	2s	512 MB	Judgeable
Stars on Shoulder BoardsGiven bounds on star counts and the min and max stars removable from officer Y, find the smallest and largest possible battalion size.	Medium5	MathImplementation+2	No attempts yet	2s	512 MB	Judgeable
ChessGiven a staircase board of column heights, place the fewest rooks so every cell shares a row or column with a rook, and print their positions.	Medium5	GreedyImplementation	No attempts yet	2s	512 MB	Judgeable
MerlinGiven n vessels with amounts of elixir, find the minimum number of vessels to empty (and smash) so the remaining vessels can be made equal by redistributing the poured elixir.	Medium5	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Olympiad RegistrationEach row was written in one of two field orders; use the guarantee that every first name appears at least twice to recover each participant's surname, given name, and patronymic, then sort by surname.	Medium5	Hash mapString+2	No attempts yet	2s	512 MB	Judgeable
DiseaseGiven m tests, each listing which bacteria it checks for and its positive or negative result, classify every bacterium as impossible, certainly present, or undetermined, or report that the results contradict each other.	Medium5	ImplementationBrute force+2	No attempts yet	2s	512 MB	Judgeable
Mysterious EquationCount ordered pairs of non-negative integers (x, y) with x + y + xy = n, where n can be as large as 10^9.	Medium5	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
HalfStarting with n apples and meeting k friends, each friend either takes half an apple or half of the current amount; list every possible final amount.	Medium5	ImplementationBrute force+2	No attempts yet	2s	512 MB	Judgeable
Time TravelGiven k trees on n cities, count for each ordered pair (s, f) how many cities lie on the s-to-f path in every tree.	Medium5	TreeBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Configuration FileParse a brace-delimited configuration file where assignments to variables are scoped to their block, and report the value assigned by each variable-to-variable assignment.	Medium5	StackHash map+2	No attempts yet	2s	512 MB	Judgeable
BarbellsSplit the weights 1 through n into three groups of equal total weight, or report that no such split exists.	Medium5	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
A Simple Sequence of DigitsGiven n and k, build the digit string formed by concatenating the first n primes, then delete exactly k digits to leave the largest possible number.	Medium5	GreedyStack+2	No attempts yet	1s	512 MB	Judgeable
Bursting the BalloonsGiven N balls and K baskets, decide whether N can be split into K distinct positive integers and, if so, print the minimum possible difference between the largest and smallest part.	Medium5	MathGreedy+2	No attempts yet	0.25s	512 MB	Judgeable
DietChoose a subset of up to 15 ingredients whose protein, fat, carbohydrate, and vitamin totals each meet a threshold, minimizing cost with the lexicographically smallest index set on ties.	Medium5	Brute forceBacktracking+2	No attempts yet	2s	512 MB	Judgeable
Connecting Rods in 3DGiven a start and end point in 3D and a multiset of rod lengths, decide whether every rod can be chained from start to end, allowing overlap and at most one rod end at each of the two points.	Medium5	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
Do You Have a Problem with Insung??On an H by W grid with obstacles of varying height, decide if Insung can reach the goal, given that each move costs 1 strength and climbing to a higher cell costs extra strength equal to the height difference.	Medium5	BFSGraph+2	No attempts yet	1s	512 MB	Judgeable
ChocolateGiven a grid of domino pieces, decide whether a full horizontal or vertical cut can split the bar without cutting through any piece.	Medium5	ImplementationArray+2	No attempts yet	2s	512 MB	Judgeable
NecklaceArrange n pearls as a binary necklace with no reflection axis of symmetry, or print -1 when no such arrangement exists.	Medium5	MathImplementation	No attempts yet	2s	512 MB	Judgeable
Unified State ExamConvert an integer x into base -2, printing the number of digits and the binary digits from least significant to most.	Medium5	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Phone NumbersGiven country codes and operator codes, split each 11-digit number into its parts and print it in the phone book format, or Incorrect.	Medium5	StringImplementation+2	No attempts yet	2s	512 MB	Judgeable
Secure ConnectionGiven a weighted undirected graph where each vertex is labeled 0, 1, or 2, find the cheapest path between any label-1 vertex and any label-2 vertex, and report its endpoints and cost.	Medium5	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Cycle GameProcess a sequence of drawn edges on n points and report the first turn at which the drawn edges form a cycle, or 0 if none appears.	Medium5	Union-findGraph+2	No attempts yet	1s	512 MB	Judgeable
Magician Shark and FireballSimulate fireballs moving on a wrapping N by N grid for K steps, merging any that share a cell and splitting each merged group into four.	Medium5	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Monomino Domino 2Place blocks on the red board, let them slide onto the green and blue boards, clear full lines, and report the total score and the remaining cell counts.	Medium5	SimulationImplementation+1	No attempts yet	1s	512 MB	Judgeable
CoinsArnavaz flips between 1 and k coins so Shahrnaz can find the cursed coin at cell c just by looking at the board.	Medium5	Bit manipulationMath	No attempts yet	1s	512 MB	Judgeable
Energy DrinkCombine N drink amounts two at a time, where pouring one into another keeps half the poured amount, and maximize the final total.	Medium5	GreedySorting+2	No attempts yet	1s	256 MB	Judgeable
Balance of BoxesGiven box centers stacked from the floor, decide whether every suffix's center of mass lies strictly inside the box just below it.	Medium5	ArrayPrefix sum+2	No attempts yet	1s	256 MB	Judgeable
Claire and PotionsGiven recipes that combine several potions into another, and an initial set of owned potions, find every potion that can be produced.	Medium5	GraphTopological sort+2	No attempts yet	1s	256 MB	Judgeable
Y-sequenceFind the smallest k such that rotating the first k elements to the end makes the sequence non-decreasing or non-increasing, or report -1.	Medium5	ArrayImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Metroidvania ExtremePrint a path from the start to the goal on a grid where key letters unlock matching doors and the hero can teleport to any visited cell.	Medium5	BFSGraph+1	No attempts yet	1s	1024 MB	Judgeable
There Is a Convenience Store Below My HouseGiven N stores each labeled with one of M brands, assign each brand to one of M days and find the minimum number of people so every store is watched exactly on its brand's day.	Medium5	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
Hoseok, the Patient Domino ArtisanSimulate R rounds of domino pushes and single-cell repairs on a grid, handling chain reactions, and report the attacker's total score and final board.	Medium5	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Hosuk Fell into String HellCount, for each of K query strings, how many move sequences on a torus grid walk through cells spelling that string, where revisits are allowed.	Medium5	Dynamic programmingBrute force+2	No attempts yet	1s	512 MB	Judgeable
Alley Boss Hoseok - FeasibilityFind a path from A to B whose total toll is at most C, minimizing the largest single toll along the way; print -1 if none exists.	Medium5	Binary searchGraph+2	No attempts yet	3s	512 MB	Judgeable
Two BuildingsGiven n building heights, find the maximum of (h_i + h_j) times (j - i) over all pairs i < j, with n up to 1,000,000.	Medium5	Two pointersGreedy	No attempts yet	1s	512 MB	Judgeable
Alley Boss Hoseok - Efficiency 1Find a path from A to B whose total toll is at most C, minimizing the largest single toll paid along the way; print -1 if no such path exists.	Medium5	GraphShortest path+2	No attempts yet	3s	512 MB	Judgeable
Selecting NumbersChoose K numbers from a row so that the sum of each chosen value minus the number of chosen values before it is maximized.	Medium5	Dynamic programmingSorting+2	No attempts yet	1s	512 MB	Judgeable
Shortened FormFind the smallest n such that S is a subsequence of T repeated n times, or -1 if no such n exists.	Medium5	GreedyString+2	No attempts yet	1s	512 MB	Judgeable
PatkiceA grid of one-way arrows carries a token from 'o'; find the starting direction that reaches 'x' in the fewest steps, breaking ties alphabetically.	Medium5	GraphSimulation+2	No attempts yet	1s	512 MB	Judgeable
Game Developer YoungwooGiven a record of coin tosses from a level-up game, list every pair of positive integers (x, y) that could have produced that record under the game rules.	Medium5	SimulationBrute force+1	No attempts yet	3s	512 MB	Judgeable
LuggageGiven a product p up to 10^15, find three positive integers whose product is p and whose sum is as small as possible.	Medium5	MathNumber theory+1	No attempts yet	10s	512 MB	Judgeable
Easy Compare-and-SetGiven n CAS operations with required success or failure and an initial value c, find an execution order that meets every wish, or report that none exists.	Medium5	GreedyImplementation+1	No attempts yet	2s	512 MB	Judgeable
Integer SquareGiven an integer area s, decide whether a square with integer-coordinate vertices can have that area, and if so output the four vertices.	Medium5	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
PyramidGiven a pyramid of n levels with alternating switches, find the exit that the k-th ball rolls to, for up to 20 test cases.	Medium5	SimulationImplementation	No attempts yet	3s	1024 MB	Judgeable
ConsultingGiven WRITE and READ commands on named memories, insert the fewest WAIT lines so that no two conflicting commands run at the same time.	Medium5	GreedyHash map+1	No attempts yet	2s	1024 MB	Judgeable
Mint ChocoGiven a chain of integer multiplications and divisions, decide whether the overall value is an integer or a non-integer rational.	Medium5	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
ThanosGiven a binary string with even counts of 0s and 1s, keep exactly half of each digit and output the lexicographically smallest subsequence that remains.	Medium5	GreedyString	No attempts yet	1s	1024 MB	Judgeable
CPU BenchmarkingGiven ratios between consecutive sorted CPUs, compute the sum over all pairs (i<j) of the product of ratios from i to j, modulo 1e9+7.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	1024 MB	Judgeable
AquariumMove k piranhas on a line of n positions from their current spots to target spots by luring them with a finger, minimizing the total seconds needed.	Medium5	GreedySimulation	No attempts yet	2s	512 MB	Judgeable
Matrix EncryptionEncrypt each message by splitting it into blocks of d characters, multiplying each block as a column vector by a given d x d integer matrix, and reducing each result modulo 30 into the range 1 to 30.	Medium5	MatrixMath+2	No attempts yet	2s	512 MB	Judgeable
Lost in SpaceGiven an N by N grid of printable ASCII characters, find every starting position and of eight directions where a query string matches, skipping blank cells and never wrapping.	Medium5	ArraySimulation+2	No attempts yet	1s	512 MB	Judgeable
Blind WalkWrite a program that drives a blind robot through an n by m maze using only bump feedback, so it visits every empty cell and then prints DONE.	Medium5	DFSGraph	No attempts yet	1s	512 MB	Judgeable
The Comeback King (Easy)Given each participant's submission history, simulate the unfreezing reveals in the specified order and find the participant with the most places gained.	Medium5	SimulationSorting	No attempts yet	1s	512 MB	Judgeable
Arrow Maze (Hard)Given an R by C grid of arrows, decide whether the visitor can reach the bottom-right room from the top-left using at most K scroll sets that rotate arrows.	Medium5	Shortest pathGraph+1	No attempts yet	3s	512 MB	Judgeable
ElevatorFind, for each employee, the second they reach floor 1, given their call times and floors and an elevator that serves one trip of calls at a time.	Medium5	SortingSimulation+1	No attempts yet	1s	512 MB	Judgeable
ZOAC 3Two fingers start on given keys of a QWERTY keyboard; consonants are typed by the left finger and vowels by the right, and moving a finger costs Manhattan distance. Find the minimum total time to type the string.	Medium5	Dynamic programmingImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Badminton TournamentCount the number of ways to remove at most 3 of N participants and then have everyone remaining draw a tag that is not their own.	Medium5	CombinatoricsMath+2	No attempts yet	1s	1024 MB	Judgeable
Interval CoveringGiven n intervals where each costs its length, find the cheapest set of intervals that covers each query range [a, b], or -1 if none does.	Medium5	Dynamic programmingIntervals+1	No attempts yet	1s	1024 MB	Judgeable
CampusFor each room number, find its floor given that each entrance has x rooms on floors divisible by k and y rooms otherwise, with room numbering continuing across entrances.	Medium5	MathBinary search+2	No attempts yet	1s	512 MB	Judgeable
Knight's ShieldTwo triangles are glued along a common side; find the minimum possible perimeter of the resulting shape.	Medium5	GeometryBrute force+2	No attempts yet	2s	512 MB	Judgeable
Sticky TapeGiven a grid of closed windows, find the fewest straight horizontal or vertical tape pieces that cover every closed cell exactly once.	Medium5	Dynamic programmingBit manipulation	No attempts yet	1s	512 MB	Judgeable
Three SonsSplit an integer n into three strictly increasing positive parts a < b < c whose squares sum to the minimum possible value.	Medium5	MathGreedy+1	No attempts yet	1s	512 MB	Judgeable
Range Sum Query KGiven a K-dimensional array of N^K values, answer box-sum queries over index ranges and apply point assignments.	Medium5	Prefix sumArray	No attempts yet	6s	512 MB	Judgeable
Permutations on the Road: AliceGiven a permutation, sum the number of inversions over every contiguous subarray. Each inversion pair contributes once for every subarray that contains both positions.	Medium5	ArrayCombinatorics+2	No attempts yet	3s	1024 MB	Judgeable
Vaccination Against CoronaGiven n positions on a line and a safe distance L, find the minimum number of people to remove so that every pair of remaining people is at least L apart.	Medium5	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Comic BingeFind the minimum time for Andi and Budi to finish all N comic books, where Budi may skip one book after each read and Andi must wait for Budi to finish any book Budi reads.	Medium5	Dynamic programmingArray	No attempts yet	1s	512 MB	Judgeable
Easy MeasurementsGiven b and d, count positive integer pairs (a, c) such that pump rates a/b and c/d sum to the combined rate 1/d per second implied by pumping b liters in d seconds.	Medium5	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Jumping JackFind the largest jump level that lets Jack reach the last checkpoint from position 0 in exactly k jumps, or report -1.	Medium5	Binary searchGreedy	No attempts yet	2s	512 MB	Judgeable
Efficient Data StructureMaintain sequences a and b under point updates and answer c_x, where c_i = max(c_{i-1} + b_i, a_i) and c_0 = 0.	Medium5	Segment treeDynamic programming	No attempts yet	5s	512 MB	Judgeable
Brewing TeaGiven K bags whose capacities are x_i and pots holding at most 10 cups, find the minimum number of pots that together serve at least N people, where each pot holds tea from a single bag.	Medium5	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Björne's StorehouseGiven each bear's sleep start date and a fixed sleep length, find the fewest hired bears who are awake on every day Björne sleeps.	Medium5	GreedyIntervals	No attempts yet	1s	1024 MB	Judgeable
RenovationAssign each needed nail to a longer or equal existing nail, or buy a new one, minimizing the number bought and then their total length.	Medium5	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
MultationerGiven strings S and T over the letters A, B, C, find the shortest sequence of multations (each replacing every copy of one letter with a string of 1 to 3 letters) that turns S into T.	Medium5	Brute forceString+1	No attempts yet	1s	1024 MB	Judgeable
Robot CompetitionGiven the tallest stack height in every row and column of an N by N grid, find the minimum and maximum total number of cubes.	Medium5	GreedyImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Meal OrderFind the minimum extra cost to move friends to pricier dishes so that at least k distinct dishes are ordered, or report -1 if impossible.	Medium5	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
The GiantGiven the cave size and the two giant feet, find one lattice point inside the cave that forms a non-degenerate obtuse triangle with the feet.	Medium5	GeometryBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Moving BoxesFind the fewest boxes to add to stack 1 so you can walk from stack 1 to stack N, pushing a box down only when your stack is at least two higher than a neighbor.	Medium5	GreedySimulation	No attempts yet	1s	1024 MB	Judgeable
Fluoride DentistGiven values a_i, Bjorn (the one with a_i=0) may reinsert himself anywhere; maximize the sum of i*a_i.	Medium5	ArrayPrefix sum+2	No attempts yet	3s	1024 MB	Judgeable
Computer DistributionGiven x desktops priced at a and y laptops priced at b, split them among n departments so the least important department gets the highest possible total value.	Medium5	Dynamic programmingBinary search	No attempts yet	3s	1024 MB	Judgeable
IOI SelectionGiven each participant's four raw contest scores and school year, normalize scores per contest, sum the final plus the two best KATT results, then pick the IOI and BOI teams.	Medium5	SortingImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Snowball Fight 2Given two increasing lists of snowball sizes thrown by Sweden and Finland, find the maximum number of throws that could have been responses in self-defense.	Medium5	GreedyTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
BelarusDecide whether coins of value 2^i (a_i of each) can pay every one of M item prices exactly, since shops never give change.	Medium5	GreedyBit manipulation	No attempts yet	1s	1024 MB	Judgeable
NangijalaGiven N people and M enemy pairs, the task is to find the fewest deaths, each moving one person to the next world, so that no enemies share a world.	Medium5	GraphBFS+1	No attempts yet	2s	1024 MB	Judgeable
QWERTY KeyboardGiven strings of uppercase letters, find the minimum typing time on a QWERTY keyboard where each keypress costs 1 second and each move between keys costs 2 seconds per step.	Medium5	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Social DistancingChoose s of n outlet positions to maximize the minimum distance between any two chosen seats.	Medium5	Binary searchGreedy+2	No attempts yet	1s	512 MB	Judgeable
That Kind of RelationshipConstruct a permutation of 1..N whose number of inversions equals K, for N up to 4242.	Medium5	GreedyImplementation+2	No attempts yet	4.242s	1042 MB	Judgeable
I Hate OverlapsGiven a sequence and a limit K, find the length of the longest contiguous subarray where no value appears more than K times.	Medium5	Sliding windowTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
Tree Trunk and BranchesGiven a rooted weighted tree, find the giga node (first node from the root with at least two children, or the single leaf), then output the trunk length and the longest branch length from the giga node to a leaf.	Medium5	TreeDFS+2	No attempts yet	2.5s	1024 MB	Judgeable
Degree Bounded Minimum Spanning TreeFind the minimum-cost spanning tree where each vertex i has degree at most b_i, or report NO if no such tree exists.	Medium5	BacktrackingMinimum spanning tree+1	No attempts yet	3s	1024 MB	Judgeable
TteokgukGiven bowl sizes, stack each bowl only on a strictly smaller one and find the minimum number of towers needed to use all bowls.	Medium5	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Attacked CityGiven an N by N grid of empty cells, buildings, and rubble, find the cells where bombs were placed so that every rubble cell is reached by a shockwave.	Medium5	SimulationImplementation	No attempts yet	3s	1024 MB	Judgeable
Artist MimiGiven up to 30 RGB paints and a target color, find the minimum difference achievable by mixing between 2 and 7 paints in equal proportions with floor division.	Medium5	Brute forceCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Yua and the Gomduri CarCount all walks of length exactly 7 in an undirected graph, where vertices and edges may repeat, modulo 1e9+7.	Medium5	Dynamic programmingMatrix+2	No attempts yet	1s	1024 MB	Judgeable