Interview core

Mediums from real onsites

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Total results3,615 problems

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
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
Unified State Exam
Medium5
Math, Number theory+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
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
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
Hoseok, the Patient Domino Artisan
Medium5
Simulation, Implementation+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
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
Patkice
Medium5
Graph, Simulation+2
No attempts yet
Time limit
1s
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
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
Arrow Maze (Hard)
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
ZOAC 3
Medium5
Dynamic programming, Implementation+1
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
Sticky Tape
Medium5
Dynamic programming, Bit manipulation
No attempts yet
Time limit
1s
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
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
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
Moving Boxes
Medium5
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Computer Distribution
Medium5
Dynamic programming, Binary search
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Belarus
Medium5
Greedy, Bit manipulation
No attempts yet
Time limit
1s
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
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
Attacked City
Medium5
Simulation, Implementation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Spy 2
Medium5
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Special Substring
Medium5
Sliding window, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Frequent Alphabet
Medium5
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Maximum Subset
Medium5
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Largest Exotic Number
Medium5
Sorting, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Inverse Common Superstring
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Adding Numbers
Medium5
Dynamic programming, Math
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Coin Stacks
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Exam Manipulation
Medium5
Brute force, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Triangular Collection
Medium5
Sorting, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Math Trade
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Oreperations Research
Medium5
Dynamic programming, Prefix sum
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Restroom Monitor
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Kangaroo Party
Medium5
Sorting, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Weird Flecks, But OK
Medium5
Geometry, Binary search+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Pulling Their Weight
Medium5
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rounds
Medium5
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Distance
Medium5
Math, Sorting+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Alias
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Year of the Cow
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Lexicographically Minimal Subsequence
Medium5
Stack, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hoseok's Two Chickens
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rätblocket
Medium5
BFS, Simulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Firewall
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Robot Vacuum
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Squirrel in the Tree
Medium5
Tree, DFS+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
3-i-rad
Medium5
Simulation, Game theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Making Consecutive Primes
Medium5
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Digit Sum
Medium5
Dynamic programming, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Football Statistics
Medium5
Hash map, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fraction
Medium5
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candles
Medium5
Geometry, Hash map+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Oil
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Wall
Medium5
Greedy, Array+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Space Invaders
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Triangular Frame
Medium5
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Automatic Friends
Medium5
Hash map, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cinema Academy
Medium5
Greedy, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dice
Medium5
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Magic Stone Toy
Medium5
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Moving the Light Stone
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Round Table
Medium5
Greedy, String+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Beautiful Sequence
Medium5
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Morning Walk
Medium5
Tree, DFS+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Shark Elementary School
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Arranging Books
Medium5
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Spy 2Given each member's spy status and interview testimonies, decide whether the constraints are consistent and output a spy or non-spy label for every member.	Medium5	GraphDFS+1	No attempts yet	2s	1024 MB	Judgeable
Special SubstringGiven a string and K, find the fewest character changes needed so some window of K consecutive characters becomes a single repeated letter.	Medium5	Sliding windowString+2	No attempts yet	1s	512 MB	Judgeable
Frequent AlphabetGiven two length-N strings S and T, choose one character from each column to maximize the count of the most frequent letter in the resulting password.	Medium5	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
Maximum SubsetGiven N integers, pick K of them to maximize the smallest gap between any two chosen values; duplicates make the gap zero.	Medium5	Binary searchGreedy+2	No attempts yet	1s	512 MB	Judgeable
Largest Exotic NumberGiven an N by N matrix, find the largest value that appears at two distinct cells where one cell is up and to the left of the other, or print -1 if none exists.	Medium5	SortingMatrix+2	No attempts yet	1s	512 MB	Judgeable
Inverse Common SuperstringGiven a string R, print the lexicographically smallest non-empty lowercase string that does not appear as a substring of R.	Medium5	StringHash map+2	No attempts yet	1s	512 MB	Judgeable
Adding NumbersGiven an array B of N integers, decide whether it can be built from all zeros by repeatedly adding (1,2) or (2,1) to two adjacent cells.	Medium5	Dynamic programmingMath	No attempts yet	0.5s	512 MB	Judgeable
Coin StacksGiven n coin stacks, repeatedly remove one coin from two different nonempty stacks; decide if all coins can be removed and print a valid sequence of moves.	Medium5	GreedyImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Exam ManipulationGiven n students' True/False answer strings of length k, choose an answer key to maximize the minimum score across all students.	Medium5	Brute forceBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Triangular CollectionCount subsets of at least three distinct positive integers in which every triple forms a valid triangle, given n up to 50.	Medium5	SortingTwo pointers+2	No attempts yet	1s	512 MB	Judgeable
Math TradeEach person has one item and wants one other item; find the longest chain of trades where each item passes to the next person.	Medium5	GraphDFS+2	No attempts yet	1s	1024 MB	Judgeable
Oreperations ResearchGiven two queues of ore carts and the capacities of train cars, decide whether whole-cart dumps can fill every car to exactly its capacity.	Medium5	Dynamic programmingPrefix sum	No attempts yet	7s	1024 MB	Judgeable
Restroom MonitorDecide whether all n people can use one of s stalls before their deadlines, when at most one toilet paper user may be inside at any time unit.	Medium5	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Kangaroo PartyGiven n distinct house positions, pick two of them as party houses so the sum of squared distances from every house to its nearest party house is minimized.	Medium5	SortingBrute force+2	No attempts yet	1s	512 MB	Judgeable
Weird Flecks, But OKGiven 3D points in a cube, find the smallest drill diameter so a bit entering perpendicular to a face removes all points, i.e. the smallest enclosing circle of the points projected onto each of the three coordinate planes.	Medium5	GeometryBinary search+2	No attempts yet	3s	1024 MB	Judgeable
Pulling Their WeightFind the smallest integer threshold t that splits the animal weights into two groups of equal total weight, with ties at t handled by pairing.	Medium5	SortingPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
RoundsEach round, every member except member i gives S credits to member i; after any round the outcome is the minimum holding, and we want the largest such minimum.	Medium5	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
DistanceGiven N points on a grid, compute the sum of Manhattan distances over all distinct pairs.	Medium5	MathSorting+2	No attempts yet	3s	1024 MB	Judgeable
AliasGiven a weighted directed graph of n words and m edges, answer q queries asking the earliest time word b is reached after word a is spoken, or report that it never happens.	Medium5	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Year of the CowGiven N statements relating each new cow's birth year to an earlier cow by the nearest zodiac year before or after, find how many years apart Bessie and Elsie were born.	Medium5	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Lexicographically Minimal SubsequenceGiven a string s and an integer k, output the lexicographically smallest length-k subsequence of s.	Medium5	StackGreedy+2	No attempts yet	2s	512 MB	Judgeable
Hoseok's Two ChickensChoose two buildings in an undirected graph to place shops so that the sum over all buildings of twice the distance to the nearest shop is minimized, breaking ties lexicographically.	Medium5	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
RätblocketFind the fewest rolls that move a 1x1x2 block from cell A to cell B on a grid with blocked cells, modulo cells, and switch cells.	Medium5	BFSSimulation	No attempts yet	1s	512 MB	Judgeable
FirewallSimulate a rule list where each packet is checked top to bottom against port, IP, and a rate limit over the last 1000 packets, printing the action for every matching rule until accept or drop.	Medium5	SimulationImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Robot VacuumA robot slides in each commanded direction until a box stops it; count the distinct grid cells it visits, including the start.	Medium5	SimulationImplementation+2	No attempts yet	1s	1024 MB	Judgeable
The Squirrel in the TreeGiven a tree rooted at node 1 and a set of nodes holding nuts, find the shortest round trip from node 1 that visits every nut node.	Medium5	TreeDFS+2	No attempts yet	4s	1024 MB	Judgeable
3-i-radPlay tic-tac-toe interactively against an opponent, reading the board after each of their moves and printing your move; end the game once either side wins or draws.	Medium5	SimulationGame theory+2	No attempts yet	1s	1024 MB	Judgeable
Making Consecutive PrimesGiven n integers, change each into a prime so the chosen primes form a contiguous block of the prime sequence, minimizing the total change.	Medium5	SortingGreedy+1	No attempts yet	1s	512 MB	Judgeable
Digit SumSplit A into two non-negative integers B and C with sum A so that their digit sums total as much as possible, then print that maximum and the split.	Medium5	Dynamic programmingMath	No attempts yet	2s	1024 MB	Judgeable
Football StatisticsProcess a stream of football match records and queries, maintaining per-team and per-player goal statistics, minutes of goals, and score-opening counts.	Medium5	Hash mapImplementation+2	No attempts yet	2s	1024 MB	Judgeable
FractionGiven n, find the largest proper fraction whose numerator and denominator are coprime and sum to n.	Medium5	Number theoryMath+2	No attempts yet	2s	1024 MB	Judgeable
CandlesGiven n candle points inside a circle and m lines that cut the cake, decide whether some region bounded by the lines contains two or more candles.	Medium5	GeometryHash map+2	No attempts yet	2s	1024 MB	Judgeable
OilGiven dollars and euros and n countries that each sell oil for a fixed dollar price or a fixed euro price, find the maximum barrels buyable when each country must be paid in a single currency.	Medium5	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
WallGiven column heights, find the minimum number of moves of taking a top block to an adjacent column so that all heights differ by at most one.	Medium5	GreedyArray+2	No attempts yet	2s	1024 MB	Judgeable
Space InvadersGiven aliens stacked in n columns and a cannon starting at column p, find the minimum number of move and fire actions to destroy every alien.	Medium5	Dynamic programmingGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Triangular FrameGiven a triangle with sides a, b, c and a frame width d, find the area of the triangular frame left after cutting out the inner triangle formed by moving each side inward by d.	Medium5	GeometryMath+2	No attempts yet	2s	1024 MB	Judgeable
Automatic FriendsCount pairs of triples that agree in exactly one coordinate and differ in the other two.	Medium5	Hash mapCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Cinema AcademyChoose two different films to win best directing and best screenplay so that the total delight, where each film contributes one of three values depending on its outcome, is maximized.	Medium5	GreedyArray+2	No attempts yet	1s	1024 MB	Judgeable
DiceGiven the first player's total from rolling some six-sided dice, find the minimum and maximum possible total on the bottom faces.	Medium5	MathGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Magic Stone ToySort a permutation of 1..N into increasing order using at most 100 reversals of adjacent segments, or report impossible.	Medium5	SortingGreedy+2	No attempts yet	1s	256 MB	Judgeable
Moving the Light StonePick drag or carry for each of N segments, paying a switch cost K whenever the choice changes, to minimize the total.	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
Round TableArrange m boys and n girls in a circle to maximize how many people have the neighbor pattern that makes them active, and output one such seating.	Medium5	GreedyString+2	No attempts yet	2s	1024 MB	Judgeable
Beautiful SequenceGiven N, print a sequence of N ones and N minus ones that maximizes the final value B_N of the recurrence B_i = B_(i-1) * A_(2i-1) + A_(2i).	Medium5	GreedyMath+1	No attempts yet	1s	256 MB	Judgeable
Morning WalkGiven a tree where each vertex is indoor or outdoor, count ordered pairs of distinct indoor vertices whose tree path has no other indoor vertex.	Medium5	TreeDFS+2	No attempts yet	3s	256 MB	Judgeable
Shark Elementary SchoolSeat students one by one in an N x N grid, choosing each seat by liking-adjacency, then empty-adjacency, then row and column, and sum the resulting satisfaction scores.	Medium5	SimulationImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Arranging BooksGiven a string of L, M, and S characters, find the minimum number of swaps of two characters needed so that all L come first, then all M, then all S.	Medium5	GreedyString+2	No attempts yet	1s	1024 MB	Judgeable