Interview warm-up

Short whiteboard warmups

Under construction

Still being built. Things may change

Total results4,880 problems

Pile Up!
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Square Coins
Medium4
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Similar Inorder Traversal
Medium4
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fatigue
Medium4
Greedy, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bus Terminal
Medium4
Sorting, Intervals+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Professor's Calculator Is Broken!
Medium4
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Linear System of Equations
Medium4
Math, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Songi's Card Game
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Recycled Problem
Medium4
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Consecutive Primes
Medium4
Number theory, Math+2
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Trash Bins
Medium4
Array, Implementation+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Othello
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Balanced Ternary
Medium4
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Suffix-Replacement Grammars
Medium4
String, BFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dogs and Cats
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Social Hierarchy
Medium4
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Web Browser 2
Medium4
Simulation, Stack+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Propagation and Merging 2
Medium4
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of Distances 2
Medium4
Sorting, Prefix sum+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Drunk Passenger
Medium4
Probability, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ice Growth
Medium4
Array, Prefix sum+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Escalator
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Kathmandu
Medium4
Array, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Backup
Medium4
Implementation, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Steve's perfectionism
Medium4
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Least Common Divisor
Medium4
String, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Find the House
Medium4
Hash map, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Trampler
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Devil's Annual Leave Calculator
Medium4
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Find the Longest Subsequence
Medium4
Bit manipulation, Array
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Marbles Tell Your Lucky Number
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Physics Experiment
Medium4
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Successful String
Medium4
String, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Player-based Team Distribution
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Card Control
Medium4
Brute force, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Knitpicking
Medium4
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
2,147,483,648 Game
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Humanities and Arts Exploration Week
Medium4
Sorting, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Certain Milk Delivery List (Easy)
Medium4
Tree, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Lampice
Medium4
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Selection Sort 2
Medium4
Simulation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bus Routes
Medium4
Greedy, Math+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
ATM Queue
Medium4
Sorting, Simulation+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Kick Start
Medium4
String, String matching+1
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Combination Lock
Medium4
Array, Math+2
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Training
Medium4
Sorting, Sliding window+2
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Building Palindromes
Medium4
Prefix sum, Hash map+2
No attempts yet
Time limit
30s
Memory limit
1024 MB
Judgeable
H-index
Medium4
Sorting, Greedy+1
No attempts yet
Time limit
50s
Memory limit
1024 MB
Judgeable
Algorithm Class - Bubble Sort 2
Medium4
Simulation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Finding the Password
Medium4
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Insertion Sort 2
Medium4
Simulation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Advertisement
Medium4
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Building Decoration
Medium4
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Arabiska
Medium4
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hockey Match
Medium4
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Boris
Medium4
Dynamic programming, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Archipelago
Medium4
Graph, Union-find+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Coins
Medium4
Game theory, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Irritating accountants
Medium4
Sorting, Hash map+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Line
Medium4
Math, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
ПАЛИНДРОМ
Medium4
String, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Honey
Medium4
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Maya the Bee
Medium4
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
РАВЕНСТВО
Medium4
Math, Brute force+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Casting
Medium4
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
BORDER
Medium4
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
MrCodeFormatGrader
Medium4
Implementation, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Stamp Cluster Combinations
Medium4
Array, Prefix sum+2
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Tic-Tac State
Medium4
Bit manipulation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Card Game
Medium4
Brute force, Combinatorics+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Algorithm Class - Breadth-First Search 1
Medium4
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Breadth-First Search 2
Medium4
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Depth-First Search 1
Medium4
DFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Depth-First Search 2
Medium4
DFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Depth-First Search 4
Medium4
DFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Depth-First Search 5
Medium4
DFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Who Owns the Prize?
Medium4
Sorting, Implementation+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Work Log
Medium4
Prefix sum, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Good Groups
Medium4
Hash map, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tetris Generation
Medium4
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Boris and Berta
Medium4
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
James's Birthday Party
Medium4
Graph, DFS
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Bowser's Pipes
Medium4
Graph, DFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Longest Palindrome
Medium4
Hash map, Greedy+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Array Interval Sum Game
Medium4
Prefix sum, Sorting+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Haiku
Medium4
Prefix sum, Hash map
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Two Machines
Medium4
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Stocks
Medium4
Brute force, Simulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ingredient Optimization
Medium4
Greedy, Simulation
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Interesting Outing
Medium4
Tree, DFS+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Number Colosseum
Medium4
Stack, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Quadratic Dissonance
Medium4
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Buying Potions
Medium4
Bit manipulation, Dynamic programming
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Number Concatenation
Medium4
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Loop of Chocolate
Medium4
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Counting Liars
Medium4
Sorting, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
KIARA is a Recursive Acronym
Medium4
String, Array+1
No attempts yet
Time limit
0.1s
Memory limit
1024 MB
Judgeable
Prom
Medium4
Sorting, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pen
Medium4
Stack, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bizmarket
Medium4
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Pile Up!Simulate a robot that moves numbered cubes between piles under specific stack rules, then report the final pile heights in ascending order.	Medium4	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Square CoinsCount the number of ways to represent each amount below 300 as a sum of square-valued coins (1, 4, 9, ..., 289), with order ignored.	Medium4	Dynamic programmingMath+2	No attempts yet	2s	512 MB	Judgeable
Similar Inorder TraversalSimulate a depth-first walk from the root that mimics inorder traversal, and count the total number of moves between nodes.	Medium4	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
FatigueOver 24 hours choose work or rest each hour; work adds A fatigue and B output while rest cuts fatigue by C, and find the most output staying at or under M.	Medium4	GreedySimulation+2	No attempts yet	1s	1024 MB	Judgeable
Bus TerminalGiven N bus arrival and departure times, find the minimum number of service spaces so that no bus ever has to wait, with departures processed before simultaneous arrivals.	Medium4	SortingIntervals+2	No attempts yet	1s	1024 MB	Judgeable
The Professor's Calculator Is Broken!Multiply N pairs of decimals given to 9 places and print each product with exactly 18 digits after the decimal point, no exponent notation.	Medium4	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Linear System of EquationsGiven N linear equations in N unknowns with a unique solution, find and print the values of x1 through xN.	Medium4	MathBrute force+2	No attempts yet	2s	512 MB	Judgeable
Songi's Card GameSimulate a Josephus-like circle of N*K cards where each removed card's value decides the next jump; report the owner and value of the final card.	Medium4	SimulationImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Recycled ProblemGiven a sequence, find the length of the longest contiguous subsequence that strictly increases then strictly decreases.	Medium4	ArrayImplementation+2	No attempts yet	2s	1024 MB	Judgeable
Consecutive PrimesFor each query Z, find the largest product of two consecutive primes that does not exceed Z.	Medium4	Number theoryMath+2	No attempts yet	15s	1024 MB	Judgeable
Trash BinsGiven a string of 0s and 1s marking houses with trash bins, sum the distance from every house to its nearest bin.	Medium4	ArrayImplementation+2	No attempts yet	20s	1024 MB	Judgeable
OthelloGiven an Othello board with Black to move, find the empty cell where placing a black stone flips the most white stones, or print PASS if no move is legal.	Medium4	SimulationImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Balanced TernaryConvert a decimal integer between -10^9 and 10^9 into its unique balanced ternary representation, printing -1 digits as the letter T.	Medium4	MathImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Suffix-Replacement GrammarsGiven a start string S, a target T, and suffix-replacement rules X to Y, find the fewest rule applications that turn S into T, or report that it is impossible.	Medium4	StringBFS	No attempts yet	2s	1024 MB	Judgeable
Dogs and CatsSimulate feeding animals in line order, adding M cat portions after each dog eats, and report whether every dog gets fed before the cat food runs out.	Medium4	SimulationImplementation+2	No attempts yet	Not set	1024 MB	Judgeable
Social HierarchyGiven each person's new rank after N people are split into K groups, recover the original ranks and print each group's ranks in ascending order.	Medium4	SimulationArray	No attempts yet	1s	1024 MB	Judgeable
Web Browser 2Simulate a web browser with backward, forward, access, and compress operations, then print the current page and both history stacks.	Medium4	SimulationStack+2	No attempts yet	1s	512 MB	Judgeable
Propagation and Merging 2Given a grid where each cell references zero, one, or two other cells, decide whether the reference graph contains a cycle.	Medium4	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Sum of Distances 2Given n coordinates on a line, compute the sum of absolute differences over all ordered pairs.	Medium4	SortingPrefix sum+2	No attempts yet	0.5s	1024 MB	Judgeable
Drunk PassengerGiven n passengers where the first sits in a random seat and each displaced passenger picks a random free seat, find the probability that the last passenger's seat is taken.	Medium4	ProbabilityMath+2	No attempts yet	1s	1024 MB	Judgeable
Ice GrowthIce thickness changes each day by a_i/5, never dropping below zero; for each person, count the days the thickness reaches their required minimum.	Medium4	ArrayPrefix sum+2	No attempts yet	1.5s	1024 MB	Judgeable
EscalatorSimulate a bidirectional escalator that carries riders in 10-second trips, where riders going against the current direction wait, and report the time the last rider exits.	Medium4	SimulationImplementation+2	No attempts yet	1s	1024 MB	Judgeable
KathmanduGiven flight length D, meal times, and required sleep T, decide whether there is a block of T consecutive minutes containing no meal.	Medium4	ArrayGreedy+1	No attempts yet	1s	1024 MB	Judgeable
BackupGiven a weekly schedule of backup levels and a recovery day, list the days whose backups are needed, in increasing order of day and level.	Medium4	ImplementationGreedy+2	No attempts yet	2s	256 MB	Judgeable
Steve's perfectionismGiven an array of positive integers, output a strictly increasing array of the same length where each element is a multiple of the matching input element, at most 1e9.	Medium4	GreedyMath	No attempts yet	1s	256 MB	Judgeable
Least Common DivisorGiven two short strings, find the shortest string that divides both, meaning it repeats a whole number of times to form each, or report that none exists.	Medium4	StringMath+2	No attempts yet	2s	512 MB	Judgeable
Find the HouseStarting from a given position, repeatedly follow the triple whose start matches the current position, then print the position reached after all triples are used.	Medium4	Hash mapSimulation+1	No attempts yet	1s	1024 MB	Judgeable
TramplerFor each starting cell of an H by W grid, follow a fixed move string and output the sum of visited cell times, or 0 if the path leaves the field.	Medium4	SimulationImplementation+2	No attempts yet	2s	256 MB	Judgeable
Devil's Annual Leave CalculatorGiven a joining date and a later date on a 30-day month, 12-month year calendar, compute total monthly and annual leave earned plus days of service.	Medium4	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
Find the Longest SubsequenceFind the longest subsequence whose bitwise AND is nonzero; this equals the largest count of elements sharing any single set bit.	Medium4	Bit manipulationArray	No attempts yet	1s	512 MB	Judgeable
Marbles Tell Your Lucky NumberSimulate repeatedly subtracting the leftmost minimum value from all other non-empty bowls until one non-empty bowl remains, and report its count.	Medium4	SimulationImplementation+1	No attempts yet	2s	1024 MB	Judgeable
Physics ExperimentRound a given integer zero or more times to any place to maximize its value, and print the maximum reachable result.	Medium4	GreedyMath+2	No attempts yet	1s	1024 MB	Judgeable
Successful StringCount substrings of a given string that contain at least one pair of equal adjacent characters.	Medium4	StringCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Player-based Team DistributionPartition N players into teams; a player with value a_i in a team of size s scores s*a_i. Maximize the total score.	Medium4	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Card ControlGiven a deck of N O cards and N X cards, find the fewest times you must move a chosen card to the top so that Junseok, who takes cards 1, 3, 5, ..., wins.	Medium4	Brute forceGreedy+1	No attempts yet	1s	1024 MB	Judgeable
KnitpickingGiven groups of socks with a type and a fit (left, right, any), find the minimum number of socks that must be drawn to guarantee a matching pair, or report impossible.	Medium4	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
2,147,483,648 GameGiven an 8x8 2048-style board and one arrow key, apply the slide-and-merge rules once and print the resulting board.	Medium4	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Humanities and Arts Exploration WeekGiven N tree positions and Q query points, output for each query the sum of absolute distances to all trees.	Medium4	SortingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
A Certain Milk Delivery List (Easy)On a tree, each type 1 query adds 1, 2, 3, ... to successive rooms along the path from u to v; type 2 queries ask the total delivered to a room.	Medium4	TreePrefix sum+2	No attempts yet	1s	512 MB	Judgeable
LampiceGiven a sequence of n colors, cut any prefix and suffix so that the remaining block is some pattern repeated exactly k times, and print that pattern.	Medium4	Brute forceImplementation+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Selection Sort 2Simulate selection sort on an array and print the array right after the K-th swap, or -1 if fewer than K swaps occur.	Medium4	SimulationSorting+2	No attempts yet	1s	512 MB	Judgeable
Bus RoutesGiven bus routes with fixed periods and a deadline D, find the latest day to start so every route can be boarded in order by D. Work backward from D, rounding each boarding down to the largest multiple of its period.	Medium4	GreedyMath+1	No attempts yet	10s	1024 MB	Judgeable
ATM QueueEach person in a queue needs a fixed amount, takes at most X per turn, and rejoins the back if more is owed; output the order in which people finish.	Medium4	SortingSimulation+2	No attempts yet	20s	1024 MB	Judgeable
Kick StartCount the substrings of a given string that begin with KICK and end with START, treating different positions as different fragments.	Medium4	StringString matching+1	No attempts yet	Not set	1024 MB	Judgeable
Combination LockGiven W wheel positions on a cycle of values 1..N, find the target value minimizing the total circular distance all wheels must travel.	Medium4	ArrayMath+2	No attempts yet	40s	1024 MB	Judgeable
TrainingChoose exactly P students and raise their skills to a common value by adding 1 per hour; find the minimum total hours.	Medium4	SortingSliding window+2	No attempts yet	15s	1024 MB	Judgeable
Building PalindromesCount how many substrings of a string can be rearranged into a palindrome, using prefix counts of each letter to check odd frequencies.	Medium4	Prefix sumHash map+2	No attempts yet	30s	1024 MB	Judgeable
H-indexGiven a stream of citation counts, report the H-index after each new paper, where the H-index is the largest h with h papers cited at least h times.	Medium4	SortingGreedy+1	No attempts yet	50s	1024 MB	Judgeable
Algorithm Class - Bubble Sort 2Simulate bubble sort on N distinct integers and print the array right after the K-th swap, or -1 if fewer than K swaps happen.	Medium4	SimulationSorting+2	No attempts yet	1s	512 MB	Judgeable
Finding the PasswordFind the smallest positive integer P such that for every element a of A, the difference a - (P mod a) equals K.	Medium4	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Insertion Sort 2Simulate insertion sort on N distinct integers and print the array right after the K-th element shift, or -1 if fewer than K shifts occur.	Medium4	SimulationSorting+2	No attempts yet	1s	512 MB	Judgeable
AdvertisementGiven a directed graph of who knows whose contact, find the minimum number of people to seed so the news reaches everyone.	Medium4	GraphDFS+2	No attempts yet	1s	1024 MB	Judgeable
Building DecorationGiven a sequence of building heights, find the length of the longest strictly increasing subsequence.	Medium4	Dynamic programmingArray+1	No attempts yet	1s	1024 MB	Judgeable
ArabiskaGiven a short sentence, remove every vowel that is followed by two or more consonants and print the words in reverse order.	Medium4	StringImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Hockey MatchGiven partial hockey statistics for two teams, fill in every value that is uniquely determined by the constraints and leave the rest as -1.	Medium4	MathImplementation+1	No attempts yet	1s	1024 MB	Judgeable
BorisGiven trains with departure times, Boris counts, and station coordinates, find the largest total of Boris counts Philip can collect while walking at 1 m/s.	Medium4	Dynamic programmingSorting	No attempts yet	2s	1024 MB	Judgeable
ArchipelagoGiven n island coordinates and a boat range d, rank each island by how many other islands are reachable through a chain of hops of length at most d.	Medium4	GraphUnion-find+2	No attempts yet	2s	1024 MB	Judgeable
CoinsPlayers alternate removing 1 to 3 coins from a pile of n; whoever takes the last coin loses. Decide whether the first player wins with optimal play.	Medium4	Game theoryMath+2	No attempts yet	1s	1024 MB	Judgeable
Irritating accountantsSort the bought items so all items of a category appear together, and the categories follow a given order; ties within a category may be ordered any way.	Medium4	SortingHash map+1	No attempts yet	3s	1024 MB	Judgeable
LineLate students repeatedly cut in one between every pair, and given the final count N, find the smallest possible initial number of students.	Medium4	MathImplementation+2	No attempts yet	0.5s	1024 MB	Judgeable
ПАЛИНДРОМGiven a string of letters, split all its characters into palindromes, using each character exactly once, and report the smallest possible number of palindromes.	Medium4	StringGreedy+2	No attempts yet	1s	1024 MB	Judgeable
HoneyPooh starts at Rabbit and must eat honey n times, each next meal at a different friend's house; find the minimum total distance traveled.	Medium4	GraphGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Maya the BeeThree flowers hold A, B, C bees in nondecreasing order; move bees so each flower holds the same number, minimizing total meters flown.	Medium4	GreedyMath+2	No attempts yet	1s	1024 MB	Judgeable
РАВЕНСТВОGiven an expression X+Y=Z written in an unknown base, find the smallest base in which the equality holds.	Medium4	MathBrute force+2	No attempts yet	1s	1024 MB	Judgeable
CastingGiven counts of tall, blue-eyed, and blonde actors, find the maximum or minimum possible number who have all three traits.	Medium4	MathCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
BORDERGiven rectangle sides a and b and strips of length k, find the minimum number of strips to cover the border when each side gets at most one piece from any cut strip.	Medium4	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
MrCodeFormatGraderGiven C total lines and the N error line numbers in increasing order, print the error and correct lines as comma-separated ranges, with the last item joined by "and".	Medium4	ImplementationSimulation+1	No attempts yet	1s	1024 MB	Judgeable
Stamp Cluster CombinationsGiven cluster sizes in a row, answer queries asking whether a target number of stamps can be formed by taking some prefix and some suffix of the clusters.	Medium4	ArrayPrefix sum+2	No attempts yet	7s	1024 MB	Judgeable
Tic-Tac StateDecode a 32-bit Tic-Tac-Toe game state from an octal number and report whether X wins, O wins, it is a cat's game, or it is still in progress.	Medium4	Bit manipulationSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Card GameEach player picks k of their cards; among all possible scores, find the minimum and maximum of \|B - A\|. With n, m up to 20, brute force over all combinations works.	Medium4	Brute forceCombinatorics+2	No attempts yet	1.5s	512 MB	Judgeable
Algorithm Class - Breadth-First Search 1Run BFS from a start vertex on an unweighted undirected graph, visiting neighbors in ascending order, and report the visit order of every vertex or 0 if unreachable.	Medium4	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Breadth-First Search 2Run BFS from a start vertex on an unweighted undirected graph, visiting neighbors in descending order, and report each vertex's visit order or 0 if unreachable.	Medium4	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Depth-First Search 1Run iterative depth-first search from vertex R on an undirected unit-weight graph, visiting neighbors in ascending order, and output each vertex's visit order or 0 if unreachable.	Medium4	DFSGraph+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Depth-First Search 2Given an undirected graph and a start vertex, run the supplied recursive DFS that visits neighbors in descending order, then print each vertex's visit position (0 if unreachable).	Medium4	DFSGraph+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Depth-First Search 4Run an iterative DFS from vertex R on an undirected graph, visiting neighbors in descending order, and print each vertex's depth in the DFS tree or -1 if unvisited.	Medium4	DFSGraph+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Depth-First Search 5Run iterative DFS from R visiting neighbors in ascending order, then sum depth times visit order over all reachable vertices.	Medium4	DFSGraph+2	No attempts yet	1s	512 MB	Judgeable
Who Owns the Prize?For each of four subjects in order, pick the highest-scoring student who has not yet won a prize, breaking ties by smaller student number.	Medium4	SortingImplementation+2	No attempts yet	4s	1024 MB	Judgeable
Work LogEach employee contributes i won on their i-th working day; given N work intervals, output the total revenue on each of the K days.	Medium4	Prefix sumArray+2	No attempts yet	2s	512 MB	Judgeable
Good GroupsGiven same-group and separate-group constraints plus the actual groups of three, count how many constraints the grouping violates.	Medium4	Hash mapImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Tetris GenerationGiven a string over the seven tetromino letters, decide whether it can appear in a sequence generated in blocks of seven, where each block is a permutation of all seven pieces.	Medium4	StringImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Boris and BertaGiven a target distance n and lengths m and c, find non-negative counts of miles and cables whose total length is as close to n as possible.	Medium4	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
James's Birthday PartyGiven a friendship graph of up to 100 people, decide whether losing any single friend pair's contact would leave someone uninvited, which means checking for a bridge edge.	Medium4	GraphDFS	No attempts yet	3s	1024 MB	Judgeable
Bowser's PipesGiven pipes that form a functional graph ending at coin rooms, for each queried pipe find the pipe that reaches the same coin room with the fewest warp rooms, ties to smallest index.	Medium4	GraphDFS	No attempts yet	2s	1024 MB	Judgeable
Longest PalindromePick some of the distinct equal-length strings and order them so the concatenation is the longest possible palindrome, then print one such palindrome.	Medium4	Hash mapGreedy+1	No attempts yet	1s	256 MB	Judgeable
Array Interval Sum GameRearrange array A to maximize the total of m given interval sums, then count the arrangements that reach that maximum modulo 1e9+7.	Medium4	Prefix sumSorting+1	No attempts yet	1.5s	512 MB	Judgeable
HaikuCount the runs of consecutive words that can be split into three lines holding 5, 7, and 5 phonetic units, where each unit is a run of vowels.	Medium4	Prefix sumHash map	No attempts yet	1s	512 MB	Judgeable
Two MachinesGiven commissioning times and rates for two machines, find the most parts made in k minutes when only one engineer can commission at a time.	Medium4	GreedyMath	No attempts yet	1s	512 MB	Judgeable
StocksGiven daily prices for N days, find the most money left after repeated all-in buys with K-times leverage and full sales.	Medium4	Brute forceSimulation	No attempts yet	2s	1024 MB	Judgeable
Ingredient OptimizationGiven deliveries with spoil times and orders that each need U leaves, find the maximum number of orders that can be filled before the first failure.	Medium4	GreedySimulation	No attempts yet	5s	1024 MB	Judgeable
Interesting OutingGiven a weighted tree, find the minimum total edge cost of a walk that visits every node, starting and ending at any nodes.	Medium4	TreeDFS+1	No attempts yet	10s	1024 MB	Judgeable
Number ColosseumEach new contestant fights the most recent opposing contestant still inside, and the task asks which team wins and which integers remain, in arrival order.	Medium4	StackSimulation	No attempts yet	1s	1024 MB	Judgeable
Quadratic DissonanceFind the point x that minimizes the larger of two given upward parabolas with the same leading coefficient, and report x and that minimum value.	Medium4	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Buying PotionsGiven N potion prices and the discounts each purchase triggers on other potions, find the minimum total cost to buy all of them in some order.	Medium4	Bit manipulationDynamic programming	No attempts yet	3s	1024 MB	Judgeable
Number ConcatenationGiven a tree with a number on each house, answer Q queries by concatenating the door numbers along each path in order, modulo 1000000007.	Medium4	TreeDFS+1	No attempts yet	1s	512 MB	Judgeable
Loop of ChocolateCompute the volume of the union of n equal spheres whose centers form a cycle and only consecutive spheres overlap.	Medium4	GeometryMath+1	No attempts yet	2s	1024 MB	Judgeable
Counting LiarsGiven N cows that each claim Bessie is at or below, or at or above, some p_i, find the fewest cows that must be lying.	Medium4	SortingPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
KIARA is a Recursive AcronymDecide whether some word in the list can be spelled by the first letters of distinct list words, with the word itself counted as one of them.	Medium4	StringArray+1	No attempts yet	0.1s	1024 MB	Judgeable
PromCount the pairs of one girl and one boy whose heights differ by at most k.	Medium4	SortingTwo pointers+1	No attempts yet	1s	128 MB	Judgeable
PenGiven a bracket string, add the fewest brackets at the start and end to make it a correct sequence, or print NIE if that is impossible.	Medium4	StackString	No attempts yet	1s	128 MB	Judgeable
BizmarketMatch items to client companies, at most one each, to maximize the sum of (A_i - B_j) over matched pairs, where a pair counts only if A_i is at least B_j.	Medium4	GreedySorting	No attempts yet	2s	1024 MB	Judgeable