Interview warm-up

Short whiteboard warmups

Under construction

Still being built. Things may change

Total results4,880 problems

Project Teams
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Moving Coins
Medium4
String, Implementation
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Measuring the Cookie's Body
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Professor's Final Exam
Medium4
Sorting, Intervals+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Game Addiction
Medium4
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Let's Shoot an Arrow!
Medium4
Hash map, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Snack Party
Medium4
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Wiggly Caterpillar Hoseok - Functional
Medium4
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Contact Tracer
Medium4
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Inverted Josephus
Medium4
Simulation, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
RREF
Medium4
Math, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
ASCII Art
Medium4
Implementation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jigsaw
Medium4
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Quilindrome
Medium4
String, String matching
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Improving Grades
Medium4
Binary search, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Distinct Numbers
Medium4
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Statistics
Medium4
Greedy, Array+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Birds Rituals
Medium4
Array, Linked list+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Proofs
Medium4
Hash map, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Social running
Medium4
Brute force, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bus Numbers
Medium4
Brute force, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
#include<scoring>
Medium4
Sorting, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Barsik
Medium4
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Roadside optimization
Medium4
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Zoo
Medium4
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Candy Necklace
Medium4
Sliding window, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Forest Fire
Medium4
Graph, BFS+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Subway Seats
Medium4
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
DuTub
Medium4
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lisp to C
Medium4
Stack, String+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Escalator
Medium4
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Flip Flow
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Memorizing English Words Is Painful
Medium4
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ice Maze
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Minseo's Emergency Surgery
Medium4
Union-find, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Just Stalling
Medium4
Sorting, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gig Combinatorics
Medium4
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Rank Problem
Medium4
Simulation, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Substring Characters
Medium4
String, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Digital Speedometer
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Smoothie Stand
Medium4
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Forced Choice
Medium4
Implementation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gratitude
Medium4
Hash map, Sorting+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Two Pirates - 2
Medium4
Sorting, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Color Robot
Medium4
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Letter Dice
Medium4
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Battle of Two Geniuses
Medium4
Game theory, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Stepping Stones
Medium4
Dynamic programming, Brute force+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Piano Gymnastics
Medium4
Prefix sum, Array+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Free food
Medium4
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cyclic Palindromes
Medium4
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Chess Battles
Medium4
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Card Shuffling
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Zoo
Medium4
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fair Sequence
Medium4
Array, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Civil Defense
Medium4
Sorting, Binary search+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Window Switching
Medium4
Simulation, Array+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Car License Plates
Medium4
Combinatorics, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Table Rendering
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Password
Medium4
String, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Simple Cron Spec
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Staircase
Medium4
Array, Greedy+2
No attempts yet
Time limit
0.25s
Memory limit
256 MB
Judgeable
Game
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Minesweeper
Medium4
Implementation, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Squarow
Medium4
Array, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
LCM of Primes
Medium4
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Task
Medium4
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Image Processing
Medium4
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
String Summarization
Medium4
Implementation, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Similar License Plates
Medium4
Hash map, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
DEX Save
Medium4
Probability, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Congress of Young Enthusiasts
Medium4
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Balloons
Medium4
Greedy, Hash map+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Prizes
Medium4
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Passport
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
String Concatenation
Medium4
Stack, String+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Mines - 5
Medium4
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Piles of Books
Medium4
Array, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
H-Index
Medium4
Sorting, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
lattice
Medium4
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
SMH
Medium4
Brute force, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Factorial Factors
Medium4
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Optic Communications
Medium4
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Math is a Physical Education Subject 3
Medium4
String, Brute force+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Chain Explosion
Medium4
Graph, BFS+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Generalized Leap Year
Medium4
Implementation, Brute force+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
jfen
Medium4
String, Implementation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Misawa's Rooted Trees
Medium4
Recursion, String+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
You Are the Judge
Medium4
Simulation, Sorting+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Sum of Consecutive Integers
Medium4
Math, Brute force+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Infected Computer
Medium4
Sorting, Graph+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Sort by Hand
Medium4
Dynamic programming, Array
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Strange Currency System
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Deadly Dice Game
Medium4
Dynamic programming, Probability
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Surrounding Area
Medium4
BFS, Matrix+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Amida, the City of Miracle
Medium4
Sorting, Simulation+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Monkey Business
Medium4
Math, Number theory+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Rolling Cubes
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
First Experience
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Get Many Persimmon Trees
Medium4
Prefix sum, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Project TeamsPair 2n students into n teams so that the smallest team skill sum is as large as possible, and print that value.	Medium4	GreedySorting+2	No attempts yet	0.5s	512 MB	Judgeable
Moving CoinsGiven two coin strings S and T and two chosen positions i and j, decide whether one two-finger move turns S into T.	Medium4	StringImplementation	No attempts yet	0.5s	512 MB	Judgeable
Measuring the Cookie's BodyGiven an N by N grid of '*' and '_' forming a cookie shape, find the heart cell and the lengths of both arms, the waist, and both legs.	Medium4	ImplementationSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Professor's Final ExamGiven N non-overlapping exams in a room open for S minutes, find the earliest start time for a new exam of length M that fits without overlap, or -1.	Medium4	SortingIntervals+2	No attempts yet	1s	1024 MB	Judgeable
Game AddictionCount shortest lattice paths between two diagonal points while staying inside the unflooded region y <= x.	Medium4	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Let's Shoot an Arrow!Given N points, find the maximum number that lie on a single ray starting from the origin.	Medium4	Hash mapMath+2	No attempts yet	1s	1024 MB	Judgeable
Snack PartyGiven N days each with one positive snack rating, pick a strictly increasing subsequence (starting above 0) to maximize the sum of chosen ratings.	Medium4	Dynamic programmingArray+2	No attempts yet	1s	1024 MB	Judgeable
Wiggly Caterpillar Hoseok - FunctionalGiven N food values and a threshold K, choose non-overlapping consecutive segments whose sums each reach K, maximizing the total excess over K.	Medium4	Dynamic programmingArray+2	No attempts yet	1s	512 MB	Judgeable
Contact TracerGiven contact events in time order and one infected user, count everyone reachable from that user through the contact graph, including the user.	Medium4	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Inverted JosephusSimulate removing every K-th person from a circle of N, reversing direction after each block of M removals, and print the removal order.	Medium4	SimulationArray+2	No attempts yet	1s	1024 MB	Judgeable
RREFCompute the reduced row echelon form of an N by M matrix of rational numbers, printing each entry as a reduced fraction.	Medium4	MathImplementation+2	No attempts yet	0.5s	1024 MB	Judgeable
ASCII ArtGiven up to 5000 integer points, draw them as 'x' marks on ASCII axes inside the smallest rectangular '#' frame, with '-' and '\|' filling empty axis cells and 'o' for the origin.	Medium4	ImplementationMatrix+1	No attempts yet	1s	512 MB	Judgeable
JigsawGiven counts of corner, edge, and centre pieces, decide whether they form a complete w by h jigsaw and output any valid dimensions.	Medium4	MathImplementation+2	No attempts yet	2s	512 MB	Judgeable
QuilindromeFind the shortest string that contains the nickname as a substring and reads as a quilindrome under the mirror table, ignoring case. Print -1 if none exists.	Medium4	StringString matching	No attempts yet	1s	512 MB	Judgeable
Improving GradesGiven counts of scores 2, 3, and 4, find the minimum number of 5s to add so the rounded mean reaches at least 4.	Medium4	Binary searchMath+2	No attempts yet	1s	512 MB	Judgeable
Distinct NumbersGiven integers a and b, count how many distinct values appear among the ten expressions a+b, a-b, a*b, a/b, a^b and their swapped forms, skipping invalid ones.	Medium4	ImplementationMath+2	No attempts yet	2s	512 MB	Judgeable
StatisticsGiven daily case counts, reduce each value (never increase) so the sequence becomes non-increasing, minimizing the total amount removed.	Medium4	GreedyArray+1	No attempts yet	2s	512 MB	Judgeable
Birds RitualsMaintain a row of named birds through insert, depart, and relocate operations, then print the final left-to-right order.	Medium4	ArrayLinked list+2	No attempts yet	2s	512 MB	Judgeable
ProofsCheck a sequence of proof lines where each line is valid only if all its assumptions appeared as conclusions on earlier lines, and report the first invalid line.	Medium4	Hash mapImplementation+2	No attempts yet	2s	512 MB	Judgeable
Social runningGiven a cycle of N locations with edge lengths, choose the start point so that the total distance run alone by all runners is minimized.	Medium4	Brute forceSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Bus NumbersFind the largest number up to m that can be written as a sum of two positive cubes in at least two distinct ways, or report none.	Medium4	Brute forceMath+2	No attempts yet	2s	512 MB	Judgeable
#include<scoring>Rank n contestants by problems solved, penalty, and last submission time, then assign each a base score from a 30-rank table, averaging ties and adding an on-site bonus.	Medium4	SortingImplementation+1	No attempts yet	2s	512 MB	Judgeable
BarsikGiven a grid and a Manhattan diamond of radius S around a kennel, decide whether the diamond blocks every path from corner (1,1) to corner (N,M).	Medium4	GeometryMath+1	No attempts yet	1s	256 MB	Judgeable
Roadside optimizationGiven a graph as an adjacency matrix of reachability, find the minimum number of roads to keep so that all reachability relations stay the same.	Medium4	GraphUnion-find+2	No attempts yet	1s	256 MB	Judgeable
ZooCount the ways to fill a row of N cages with species from K options so no two adjacent cages share a species or belong to the same quarrel group.	Medium4	Dynamic programmingBit manipulation+2	No attempts yet	1s	1024 MB	Judgeable
Candy NecklaceGiven a circular necklace of B and V candies with even length, choose a split into two equal halves that maximizes the number of B's in one half.	Medium4	Sliding windowPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Forest FireOn an infinite grid where fire spreads to four neighbors and cut trees block it, count the trees still burning after T minutes.	Medium4	GraphBFS+1	No attempts yet	3s	1024 MB	Judgeable
Subway SeatsGiven counts of groups of size 1 to 4, find the minimum number of four-seat rows needed so no group is split across rows.	Medium4	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
DuTubGiven N videos, each with a length and a set of categories among at most 10, choose a subset that covers every category while minimizing total length.	Medium4	Bit manipulationDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Lisp to CConvert a nested Lisp function call, given as a single line, into the equivalent C function call syntax with commas and parentheses.	Medium4	StackString+2	No attempts yet	1s	1024 MB	Judgeable
EscalatorGiven escalator length, standing and walking speeds, two entry rates, and two queue lengths, decide which line reaches the top first.	Medium4	MathSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Flip FlowAn hourglass starts with all sand at the bottom, is flipped at given times, and you report how long after time t the sand finishes returning to the bottom.	Medium4	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Memorizing English Words Is PainfulCount each word of length at least M, then sort the distinct words by frequency descending, length descending, and alphabetical order.	Medium4	Hash mapSorting+2	No attempts yet	1s	1024 MB	Judgeable
Ice MazeFind the least total slipperiness time for Tera to reach the exit by sliding on ice and stopping only at rocks, or report -1 if escape is impossible.	Medium4	Shortest pathGraph+1	No attempts yet	1s	1024 MB	Judgeable
Minseo's Emergency SurgeryGiven an undirected graph with N vertices and M edges, find the minimum number of edge insertions and deletions needed to turn it into a tree.	Medium4	Union-findGraph+2	No attempts yet	1s	1024 MB	Judgeable
Just StallingCount the number of ways to match N cows to N stalls so that each cow's height fits within its stall's limit.	Medium4	SortingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Gig CombinatoricsCount subsequences of a rating sequence that start with 1, end with 3, and have only 2s in between, modulo 1e9+7.	Medium4	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
A Rank ProblemSimulate a ranking list where the winner of a game moves directly above the loser if the winner was ranked lower, and output the final order.	Medium4	SimulationArray+2	No attempts yet	1s	1024 MB	Judgeable
Substring CharactersFor each string, count distinct proper substrings that use exactly the same set of characters as the whole string and cannot be shortened at either end.	Medium4	StringTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
Digital SpeedometerApply hysteresis thresholds to a stream of sensor speeds so the integer display only changes when a reading crosses past the rising or falling threshold.	Medium4	ImplementationSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Smoothie StandGiven the amounts of k ingredients on hand and r recipes, each using some ingredients and having a price, find the maximum revenue from making as many smoothies of one recipe as possible.	Medium4	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
Forced ChoiceGiven a fixed sequence of card subsets chosen by the princess, decide for each step whether Puff must keep or remove those cards so that a named prediction card survives to the end.	Medium4	ImplementationGreedy+2	No attempts yet	1s	1024 MB	Judgeable
GratitudeCount how often each line appears across 3N notes, then output the K most frequent, breaking ties by which appeared most recently.	Medium4	Hash mapSorting+2	No attempts yet	3s	512 MB	Judgeable
Two Pirates - 2Given treasure costs, the first pirate always takes the largest remaining item and the second takes a random one; find both expected totals.	Medium4	SortingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Color RobotChoose N color commands so a robot, which jumps right to the next square of the commanded color, ends as far right as possible.	Medium4	Dynamic programmingString	No attempts yet	1s	1024 MB	Judgeable
Letter DiceCount how many of the M given words can be spelled by assigning each letter position to a distinct die that shows that letter.	Medium4	GraphDFS+1	No attempts yet	1s	1024 MB	Judgeable
Battle of Two GeniusesGiven a sequence of tic-tac-toe moves, print after each prefix whether the first player wins, the second player wins, or the game is a draw under optimal play.	Medium4	Game theoryBrute force+1	No attempts yet	2s	512 MB	Judgeable
Stepping StonesFind the least energy to reach the last stone using small jumps, big jumps, and one optional very big jump that costs K.	Medium4	Dynamic programmingBrute force+2	No attempts yet	1s	1024 MB	Judgeable
Piano GymnasticsGiven an array, for each query (x, y) count indices i in [x, y-1] where a[i] > a[i+1].	Medium4	Prefix sumArray+1	No attempts yet	0.5s	1024 MB	Judgeable
Free foodGiven each person's boss in a tree and a set of people at a table, count those with no ancestor also present at the table.	Medium4	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
Cyclic PalindromesGiven a lowercase word of up to 100 letters, decide whether some cyclic shift of it is a palindrome.	Medium4	StringString matching+2	No attempts yet	2s	1024 MB	Judgeable
Chess BattlesGiven one white and one black chess piece on distinct squares, decide whether each attacks the other and report NONE, WHITE, BLACK, or BOTH.	Medium4	ImplementationMath+2	No attempts yet	2s	1024 MB	Judgeable
Card ShufflingGiven a deck string read from the bottom and a repeat count k, simulate the shuffle where cards alternate into left and right piles and the left pile is placed on top, k times.	Medium4	ImplementationSimulation+2	No attempts yet	2s	1024 MB	Judgeable
ZooCount the ways to pick three animals of pairwise different species, given the population of each species.	Medium4	CombinatoricsMath+1	No attempts yet	2s	1024 MB	Judgeable
Fair SequenceGiven an odd-length binary string, find an index whose removal leaves equal numbers of ones in odd and even positions, or output 0.	Medium4	ArrayPrefix sum+2	No attempts yet	2s	1024 MB	Judgeable
Civil DefenseGiven positions of n villages and m shelters on a line, output for each village the 1-based index of the shelter closest to it.	Medium4	SortingBinary search+2	No attempts yet	2s	1024 MB	Judgeable
Window SwitchingSimulate a circular list of running applications, inserting new ones at the front and rotating on each Alt+Tab, then print each window that becomes active.	Medium4	SimulationArray+2	No attempts yet	2s	1024 MB	Judgeable
Car License PlatesGiven a valid Russian plate (letter, three digits, two letters), list every distinct plate formed by permuting its three digits and its three letters.	Medium4	CombinatoricsImplementation+2	No attempts yet	2s	1024 MB	Judgeable
Table RenderingGiven per-row cell widths, draw an ASCII table where each horizontal separator has a '+' exactly under or over every vertical bar.	Medium4	ImplementationSimulation+2	No attempts yet	2s	1024 MB	Judgeable
PasswordGiven two numbers where one digit group of the first is replaced by its digit sum to get the second, print the 1-based start and end positions of that group.	Medium4	StringTwo pointers+1	No attempts yet	1s	1024 MB	Judgeable
Simple Cron SpecParse cron-like hour, minute, and second fields, then count distinct seconds covered by at least one job and the total number of job starts.	Medium4	ImplementationSimulation+2	No attempts yet	4s	1024 MB	Judgeable
StaircaseGiven column heights, find the longest contiguous run where the i-th column from the left has height at least i.	Medium4	ArrayGreedy+2	No attempts yet	0.25s	256 MB	Judgeable
GameSimulate a game where each round starts at score n and non-negative generator values are subtracted only when they do not push the score below zero; report the number of completed rounds and the final score.	Medium4	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
MinesweeperGiven a black and white grid, build a minesweeper map where white cells are empty and black cells hold a mine or a number from 1 to 8, or report that none exists.	Medium4	ImplementationGreedy	No attempts yet	2s	1024 MB	Judgeable
SquarowFor each color, count how many blocks remain after deleting that color, accounting for neighboring blocks of the same color merging, and report the best color.	Medium4	ArrayImplementation+2	No attempts yet	1s	512 MB	Judgeable
LCM of PrimesGiven a sequence of N numbers, take the prime values among them and print their least common multiple, or -1 if none are prime.	Medium4	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
TaskGiven a DAG of task dependencies, count how many tasks must be completed before a given task X.	Medium4	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Image ProcessingRead an N by M grid of RGB triples, binarize each pixel by whether its average meets threshold T, then count the connected components of 255 pixels under 4-directional adjacency.	Medium4	BFSGraph+2	No attempts yet	1s	512 MB	Judgeable
String SummarizationGiven a string of sentences joined without spaces, shorten it to at most 25 characters using one of three fixed omission rules.	Medium4	ImplementationString+2	No attempts yet	1s	512 MB	Judgeable
Similar License PlatesGroup n equal-length license plates by their case-insensitive letter multiset plus uppercase count, then count pairs within each group.	Medium4	Hash mapString+2	No attempts yet	1s	512 MB	Judgeable
DEX SaveCompute the probability a d20 saving throw succeeds, given difficulty, modifier, advantage or disadvantage, and up to five bonus or penalty dice.	Medium4	ProbabilityBrute force+2	No attempts yet	2s	512 MB	Judgeable
Congress of Young EnthusiastsCount the ways to seat n mathematicians and n philosophers in 2n chairs of types 1, 2, and 3, modulo 10^9 + 7.	Medium4	CombinatoricsMath	No attempts yet	2s	256 MB	Judgeable
BalloonsGiven n balloons with colors and a number k, choose exactly k balloons so the number of distinct colors is maximized, and print their colors.	Medium4	GreedyHash map+2	No attempts yet	2s	256 MB	Judgeable
PrizesDistribute d candies among n ranked teams so that per-member counts strictly decrease by rank and sum to exactly d, or report impossibility.	Medium4	GreedyMath+1	No attempts yet	2s	256 MB	Judgeable
PassportGiven an arrival time and n windows with opening hours and service durations, find the earliest time the visitor finishes all windows in order, or report that it is impossible.	Medium4	SimulationImplementation+2	No attempts yet	2s	256 MB	Judgeable
String ConcatenationGiven a string of lowercase letters and parentheses, where parentheses reverse the enclosed segment, output the resulting concatenated string.	Medium4	StackString+1	No attempts yet	2s	256 MB	Judgeable
Mines - 5Given each cell's count of mines in its 3x3 neighborhood, the task is to restore the H x W mine layout that produces those counts.	Medium4	GreedySimulation	No attempts yet	1s	512 MB	Judgeable
Piles of BooksCount the tiles whose pile height is strictly greater than every pile between it and the boundary along the student's line of sight from all four sides.	Medium4	ArrayImplementation+2	No attempts yet	1s	512 MB	Judgeable
H-IndexGiven the citation counts of n papers, find the largest H such that at least H papers have at least H citations each.	Medium4	SortingArray+2	No attempts yet	1s	512 MB	Judgeable
latticeGiven three non-collinear integer points with coordinates up to 2^1024, count the lattice points on the triangle's perimeter, including the vertices.	Medium4	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
SMHGiven heights of up to 11 students in a line, find the maximum number of other students any single student can see, where sight is blocked by any head on the segment.	Medium4	Brute forceGeometry+2	No attempts yet	1s	512 MB	Judgeable
Factorial FactorsFor each N up to 100,000, count the distinct prime factors of N! and the total number of prime factors with multiplicity.	Medium4	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Optic CommunicationsMaintain a visibility graph under edge insertions and deletions, then flood each sent message through currently visible neighbors and report per-survivor received messages in order.	Medium4	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Math is a Physical Education Subject 3Given the concatenation of all integers from A to B, recover A and B, choosing the smallest A if several pairs fit.	Medium4	StringBrute force+2	No attempts yet	1s	1024 MB	Judgeable
Chain ExplosionStarting from one bomb, count how many bombs explode when each explosion detonates bombs up to D cells away along its row and column, chaining until nothing new detonates.	Medium4	GraphBFS+2	No attempts yet	8s	512 MB	Judgeable
Generalized Leap YearFor each test case, count integers x in [l, r] that satisfy a generalized leap year rule defined by a list of divisors A.	Medium4	ImplementationBrute force+2	No attempts yet	8s	512 MB	Judgeable
jfenGiven a board in jfen notation and a move command, apply the move and re-output the board in jfen notation.	Medium4	StringImplementation+2	No attempts yet	8s	512 MB	Judgeable
Misawa's Rooted TreesParse two binary trees given in a nested bracket notation, overlay them recursively, and print the resulting tree in the same notation.	Medium4	RecursionString+2	No attempts yet	10s	512 MB	Judgeable
You Are the JudgeGiven a contest log of correct and wrong submissions, compute each team's solved count and penalty, then print teams in rank order.	Medium4	SimulationSorting+2	No attempts yet	8s	512 MB	Judgeable
Sum of Consecutive IntegersFor each N up to 1000, count how many ways N can be written as a sum of two or more consecutive positive integers.	Medium4	MathBrute force+2	No attempts yet	8s	512 MB	Judgeable
Infected ComputerGiven packets with send times between computers, count how many computers get infected starting from computer 1, where a computer is infected only when it receives a packet from an already infected computer.	Medium4	SortingGraph+2	No attempts yet	8s	512 MB	Judgeable
Sort by HandGiven a permutation of n books (n at most 20), find the minimum number of single-book insertions needed to sort the shelf, or report impossible.	Medium4	Dynamic programmingArray	No attempts yet	8s	512 MB	Judgeable
Strange Currency SystemGiven a multiset of up to 10000 bill values, find the smallest positive amount that cannot be formed as a subset sum.	Medium4	GreedySorting+2	No attempts yet	8s	512 MB	Judgeable
Deadly Dice GameGiven a ring of red and black cells, find the start cell that maximizes the chance of landing on red after T die rolls moving clockwise.	Medium4	Dynamic programmingProbability	No attempts yet	8s	512 MB	Judgeable
Surrounding AreaCount empty cells that flood fill from black stakes can reach without touching white stakes, and the symmetric count for white stakes.	Medium4	BFSMatrix+1	No attempts yet	8s	512 MB	Judgeable
Amida, the City of MiracleGiven n vertical lines and m horizontal rungs at various heights, trace line a downward, switching lines at each rung, and report the final line. Multiple datasets end with 0 0 0.	Medium4	SortingSimulation+1	No attempts yet	8s	512 MB	Judgeable
Monkey BusinessGiven N doors toggled by monkeys in rounds of 1 through N, print the door numbers left open, one per line, with a blank line between test cases.	Medium4	MathNumber theory+2	No attempts yet	8s	512 MB	Judgeable
Rolling CubesSimulate rolling a 1x2x4 block on a grid and report its new corner position plus the colors on its front, left, and top faces.	Medium4	SimulationImplementation+2	No attempts yet	8s	512 MB	Judgeable
First ExperienceSimulate a four-digit calculator with registers for result, input, and pending operator, printing E once an intermediate value falls outside 0 to 9999.	Medium4	SimulationImplementation+1	No attempts yet	8s	512 MB	Judgeable
Get Many Persimmon TreesGiven tree coordinates in a W by H grid and a fixed S by T window, find the window placement containing the most trees.	Medium4	Prefix sumArray+2	No attempts yet	2s	512 MB	Judgeable