Interview warm-up

Short whiteboard warmups

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Still being built. Things may change

Total results4,880 problems

Minimum Queen Moves
Medium4
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ax+Bsin(x)=C
Medium4
Binary search, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Falling Apples
Medium4
Simulation, Implementation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Periodic Strings
Medium4
String, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mismatched Socks
Medium4
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindromes
Medium4
String, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Obfuscated Trees
Medium4
Tree, Recursion+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Door to the Treasure Repository
Medium4
Number theory, Math+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Overwatch World Cup
Medium4
Implementation, Hash map
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Careful Ascent
Medium4
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Contest Score
Medium4
Simulation, Heap+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gravity
Medium4
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hidden Palindrome
Medium4
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Arrival Time
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tandem Bicycle
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tunnel
Medium4
Array, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Amusement Park Queue
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Wheat Harvest
Medium4
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum of Divisor Sums
Medium4
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Counting Haybales
Medium4
Sorting, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Road work and the distance to the capital
Medium4
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The nearest convenience store
Medium4
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Box Packing
Medium4
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Merging Slimes
Medium4
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jump Jump
Medium4
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Company culture 1
Medium4
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Safe Squares (Small)
Medium4
Dynamic programming, Matrix+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Evaluation Order of Assignments (Small)
Medium4
Graph, Topological sort+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Close Match (Small)
Medium4
Brute force, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Last Word (Large)
Medium4
Greedy, String+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Revenge of the Pancakes (Large)
Medium4
Greedy, String+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Beach
Medium4
Implementation, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Overtime
Medium4
Hash map, Stack+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Resource Mining
Medium4
Dynamic programming, Matrix+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Cow Tipping
Medium4
Greedy, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hunter's Apprentice
Medium4
Geometry, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gwailnori
Medium4
Simulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
When Geudae Becomes Geumeo
Medium4
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rolling a Dice
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Robot Vacuum Cleaner
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Yin and Yang Stones
Medium4
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bovine Genomics (Silver)
Medium4
Brute force, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Street light poles
Medium4
Implementation, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The fastest road to Banikoara
Medium4
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Additive and multiplicative inverses
Medium4
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prerequisite Courses
Medium4
Graph, Topological sort+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Image quilting (large)
Medium4
Dynamic programming, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pizza (Large)
Medium4
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Chonggang Chonggang
Medium4
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Frozen Food
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Need for Speed
Medium4
Binary search, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Secret Chamber at Mount Rushmore
Medium4
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
A Taste of Queries
Medium4
Array, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Stephen Query
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
The TA is a sadist!!
Medium4
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
STOP USING MONEY
Medium4
Sorting, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cut Vertices and Bridges
Medium4
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Venue Rental (Small)
Medium4
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Pizza Boxes
Medium4
Array, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Steed 2: Cruise Control (Small)
Medium4
Math, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Ample Syrup (Small)
Medium4
Brute force, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Jaehong's Ladder
Medium4
Math, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of all pairwise products
Medium4
Math, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Almost Identical Programs
Medium4
String, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Forbidden Zero
Medium4
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Filling an Arithmetic Sequence
Medium4
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Police Station
Medium4
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Wet Rock Peg Plan
Medium4
Simulation, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Olympiad Pizza
Medium4
Queue, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Frosh Week
Medium4
Greedy, Two pointers+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
ZigZag
Medium4
Sorting, Hash map+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Street Lights
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
How to Eat at a Buffet
Medium4
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Frosting on the Cake
Medium4
Array, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
GlitchBot
Medium4
Simulation, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Wizard of Odds
Medium4
Math, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Treasure Hunt
Medium4
Simulation, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Bovine Shuffle
Medium4
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Milk Measurement
Medium4
Simulation, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Coloring Intervals
Medium4
Sorting, Intervals+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Window
Medium4
Array, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Best Matched Pair
Medium4
Implementation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
N and M (7)
Medium4
Backtracking, Recursion+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
N and M (9)
Medium4
Backtracking, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
N and M (11)
Medium4
Backtracking, Recursion+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
N and M (12)
Medium4
Backtracking, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Othello
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Word Search in a Grid
Medium4
Array, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
N-Step Syllogism
Medium4
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Jujisu
Medium4
Prefix sum, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting equilateral triangles
Medium4
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Big Integer A+B
Medium4
Implementation, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hoofball
Medium4
Sorting, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Taming the Herd
Medium4
Greedy, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lemonade Line
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Segmentation
Medium4
Hash map, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Balance Stone
Medium4
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Aku Negaraku
Medium4
Simulation, Array+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Binary Counting
Medium4
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Au au ua ui ya!!
Medium4
Intervals, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Minimum Queen MovesGiven a queen's start and target square on an 8x8 board, print the minimum number of queen moves needed.	Medium4	MathImplementation+1	No attempts yet	2s	512 MB	Judgeable
Ax+Bsin(x)=CGiven A, B, C with B <= A, find the unique real x solving Ax + B*sin(x) = C, rounded to six decimals.	Medium4	Binary searchMath	No attempts yet	2s	512 MB	Judgeable
Falling ApplesLet apples fall under gravity in a grid with fixed obstacles until none can move, then print the final grid.	Medium4	SimulationImplementation	No attempts yet	5s	512 MB	Judgeable
Periodic StringsGiven a string, find the smallest k such that cutting it into blocks of length k makes each block a one-step rotation of the previous block.	Medium4	StringBrute force+2	No attempts yet	2s	512 MB	Judgeable
Mismatched SocksGiven counts of socks per color, find the maximum number of pairs where each pair uses two different colors and every sock is in at most one pair.	Medium4	GreedyMath+1	No attempts yet	2s	512 MB	Judgeable
PalindromesFor each string, find the leftmost single-character deletion that leaves a palindrome, or report that none exists.	Medium4	StringTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
Obfuscated TreesDecode a tree from its obfuscated token stream, where each internal node carries an ordering code and subtree count, then print its values in pre-order.	Medium4	TreeRecursion+1	No attempts yet	2s	512 MB	Judgeable
The Door to the Treasure RepositoryFor each pair of integers, compute each key number (largest distinct prime factor minus the sum of the others) and print the one with the larger key.	Medium4	Number theoryMath+2	No attempts yet	8s	512 MB	Judgeable
Overwatch World CupOne seat in an N by N grid breaks the rule that every row and column holds each team once; find the seat and the correct shirt.	Medium4	ImplementationHash map	No attempts yet	2s	512 MB	Judgeable
Careful AscentGiven a target point and vertical strips that scale horizontal speed, find the launch horizontal velocity so the craft reaches the target at vertical speed 1.	Medium4	MathImplementation+2	No attempts yet	2s	512 MB	Judgeable
Contest ScoreSimulate reading problems in order but solving the shortest available one first, keeping at most k in memory, and report the total submission time.	Medium4	SimulationHeap+1	No attempts yet	2s	512 MB	Judgeable
GravityApples fall straight down until they rest on obstacles or the floor; print the final grid.	Medium4	SimulationImplementation	No attempts yet	1s	512 MB	Judgeable
Hidden PalindromeGiven a word of at most 40 lowercase letters, find the longest palindromic subsequence obtainable by deleting letters from the front and back.	Medium4	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Arrival TimeSimulate a drive that takes 2 hours normally but twice as long while traffic runs 07:00-10:00 and 15:00-19:00, given an on-the-hour, :20, or :40 departure.	Medium4	SimulationImplementation+1	No attempts yet	2s	512 MB	Judgeable
Tandem BicyclePair each Dmojistan rider with a Pegland rider to minimize or maximize the sum of the larger speed in each pair.	Medium4	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
TunnelGiven the entry order and exit order of N cars through a tunnel, count how many cars must have overtaken another car.	Medium4	ArrayHash map+2	No attempts yet	2s	512 MB	Judgeable
Amusement Park QueueTwo people walk a fixed grid path one step per minute, offset by K minutes; count the minutes their cells touch in any of eight directions.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Wheat HarvestFind each connected block of 1s, order blocks by area, and label every cell with its block's rank.	Medium4	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
Sum of Divisor SumsGiven L and R, compute the sum of divisor sums f(n) for every n from L to R.	Medium4	MathNumber theory+1	No attempts yet	1s	64 MB	Judgeable
Counting HaybalesGiven N distinct haybale positions and Q interval queries, count how many positions fall inside each inclusive range [A, B].	Medium4	SortingBinary search+2	No attempts yet	2s	512 MB	Judgeable
Road work and the distance to the capitalAfter each of q edge insertions and deletions, output the shortest-path distance from every city to city 1, or -1 if unreachable.	Medium4	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
The nearest convenience storeGiven an undirected weighted graph with some vertices marked as homes and others as stores, pick the home whose shortest-path distance to the nearest store is smallest, breaking ties by vertex number.	Medium4	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Box PackingGiven box sizes in order, find the longest subsequence where each box is strictly smaller than the next, counting boxes in the pile.	Medium4	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
Merging SlimesMerge N slimes two at a time, scoring the product of merged sizes, and maximize the total score.	Medium4	GreedySorting	No attempts yet	2s	512 MB	Judgeable
Jump JumpGiven jump distances on a row of n stones, count how many stones are reachable from a starting stone via left or right jumps that stay on the bridge.	Medium4	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Company culture 1Given each employee's manager and a list of praises, propagate every praise value down the whole subtree and print the total each employee receives.	Medium4	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Safe Squares (Small)Count all axis-aligned D by D subgrids of an R by C grid that contain no monster cell.	Medium4	Dynamic programmingMatrix+2	No attempts yet	5s	512 MB	Judgeable
Evaluation Order of Assignments (Small)Given assignment statements where each expression is a function call, decide whether some order evaluates every variable, which fails exactly when a dependency cycle exists.	Medium4	GraphTopological sort+2	No attempts yet	5s	1024 MB	Judgeable
Close Match (Small)Fill in the question marks in two equal-length digit strings to minimize the absolute difference between the values, breaking ties by minimizing the first then the second.	Medium4	Brute forceImplementation+2	No attempts yet	5s	512 MB	Judgeable
The Last Word (Large)Insert each letter of S at the front or back of the growing word so the final string is as large as possible lexicographically.	Medium4	GreedyString+1	No attempts yet	5s	512 MB	Judgeable
Revenge of the Pancakes (Large)Given a stack of pancakes as a string of + and -, find the minimum number of top-prefix flips needed to make every pancake show its happy side.	Medium4	GreedyString+1	No attempts yet	5s	512 MB	Judgeable
BeachCount the hexagon edges that separate land from water, ignoring any edge on the outer border of the map.	Medium4	ImplementationMatrix+2	No attempts yet	2s	512 MB	Judgeable
OvertimeGiven timestamped enter and leave records, count overtime as unmatched leaves plus unmatched enters per name after pairing.	Medium4	Hash mapStack+2	No attempts yet	2s	512 MB	Judgeable
Resource MiningA robot walks from the top-left to the bottom-right cell of an N by M grid using only right and down moves; find the largest number of resource cells it can pass through.	Medium4	Dynamic programmingMatrix+2	No attempts yet	2s	256 MB	Judgeable
Cow TippingGiven an N by N grid of 0s and 1s, find the minimum number of upper-left rectangles to toggle so all cells become 0.	Medium4	GreedyArray+2	No attempts yet	2s	512 MB	Judgeable
Hunter's ApprenticeGiven the vertices of a simple polygon in the order placed, decide whether they run counter-clockwise (print fight) or clockwise (print run).	Medium4	GeometryMath	No attempts yet	2s	512 MB	Judgeable
GwailnoriGiven each segment's bot cycle of a seconds with b active, find the earliest time to traverse all N segments in order, waiting whenever a segment is active on arrival.	Medium4	SimulationMath+2	No attempts yet	2s	512 MB	Judgeable
When Geudae Becomes GeumeoGiven N characters and M replacement pairs, find the minimum number of substitutions needed to convert character a into character b.	Medium4	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
Rolling a DiceRoll a dice on an N by M grid, updating the cell under it and the dice faces each move, and print the top face after every successful move.	Medium4	SimulationImplementation+1	No attempts yet	2s	512 MB	Judgeable
Robot Vacuum CleanerSimulate a robot vacuum that cleans cells, rotating counterclockwise and moving forward or backward, and count how many cells it cleans before stopping.	Medium4	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Yin and Yang StonesGiven a circular string of black and white stones, decide whether repeated merges can reduce it to one black and one white stone.	Medium4	StringGreedy+1	No attempts yet	2s	512 MB	Judgeable
Bovine Genomics (Silver)Count triples of genome positions where no spotty cow and plain cow share the same three characters.	Medium4	Brute forceHash map+2	No attempts yet	2s	512 MB	Judgeable
Street light polesGiven a binary r by c grid, find the minimum number of cell flips so every row has equal pole count and every column has equal pole count, or -1 if impossible.	Medium4	ImplementationMath	No attempts yet	2s	512 MB	Judgeable
The fastest road to BanikoaraGiven towns joined by undirected weighted roads, find the shortest travel distance between a named departure town and destination town.	Medium4	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Additive and multiplicative inversesGiven N and A, print the additive inverse of A modulo N and the multiplicative inverse if it exists, otherwise -1.	Medium4	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Prerequisite CoursesGiven prerequisite pairs between courses, find the earliest semester each course can be completed when unlimited courses may be taken per semester.	Medium4	GraphTopological sort+2	No attempts yet	5s	256 MB	Judgeable
Image quilting (large)Given two grayscale overlap regions of H rows and W columns, pick one column per row so adjacent rows differ by at most one, minimizing the total squared pixel difference.	Medium4	Dynamic programmingMatrix+1	No attempts yet	1s	512 MB	Judgeable
Pizza (Large)Split a tower of N into unit towers, scoring the product of the two parts at each split, and maximize the total score.	Medium4	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
Chonggang ChonggangRun a single-source shortest path from Jinseo's house, find the nearest type A and type B house, and report the closer type (A wins ties).	Medium4	Shortest pathGraph+2	No attempts yet	1s	256 MB	Judgeable
Frozen FoodCount the minutes from a start time to an end time, inclusive, whose HH:MM display contains the digit N at least once.	Medium4	ImplementationSimulation+2	No attempts yet	1s	128 MB	Judgeable
Need for SpeedGiven segment distances and speedometer readings plus a total time, find the constant offset c making the summed travel times equal t.	Medium4	Binary searchMath+1	No attempts yet	1s	512 MB	Judgeable
Secret Chamber at Mount RushmoreGiven directed letter translations, decide for each pair of words whether every letter of the first can reach the matching letter of the second.	Medium4	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
A Taste of QueriesGiven a sequence of n numbers, process q queries that either report a range sum and then swap two positions, or report one range sum minus another.	Medium4	ArrayPrefix sum+2	No attempts yet	2s	256 MB	Judgeable
Stephen QuerySimulate N rounds of survival rock paper scissors and report the longest number of consecutive wins by any single player.	Medium4	SimulationImplementation+1	No attempts yet	2s	256 MB	Judgeable
The TA is a sadist!!Given a permutation of 1 to N, find the minimum number of elements to remove so the remaining values increase from front to back.	Medium4	Dynamic programmingBinary search+2	No attempts yet	2s	256 MB	Judgeable
STOP USING MONEYSort N games by satisfaction-to-price ratio, then by lower price, then by game number, and print the first K game numbers.	Medium4	SortingMath+2	No attempts yet	1s	512 MB	Judgeable
Cut Vertices and BridgesGiven a tree with N vertices and queries, report for each query whether a specified vertex is a cut vertex or a specified edge is a bridge.	Medium4	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Venue Rental (Small)Given up to 100 axis-aligned rectangles, find the area of the union of all rectangles.	Medium4	ArrayImplementation+2	No attempts yet	2s	256 MB	Judgeable
Pizza BoxesGiven a grid of distinct pile heights, find how many boxes can be removed while keeping the per-row and per-column maxima unchanged.	Medium4	ArrayGreedy+2	No attempts yet	1s	512 MB	Judgeable
Steed 2: Cruise Control (Small)Given horses ahead on a one-way road that slow to match slower horses they catch, find the fastest constant speed Annie can hold to her destination without ever passing one.	Medium4	MathImplementation+2	No attempts yet	5s	512 MB	Judgeable
Ample Syrup (Small)Choose K pancakes from at most 10 to stack largest radius on the bottom, maximizing the exposed surface area divided by pi.	Medium4	Brute forceSorting+2	No attempts yet	5s	512 MB	Judgeable
Jaehong's LadderGiven a rectangle's width, height, and a number of vertical strips, sum the lengths of the N-1 rungs where the strips cross the rectangle's diagonals.	Medium4	MathGeometry+2	No attempts yet	2s	512 MB	Judgeable
Sum of all pairwise productsGiven n integers, compute the sum of x_a * x_b over all pairs with a < b.	Medium4	MathPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Almost Identical ProgramsGiven two program strings, decide whether they are identical, differ only in one string literal at the same position, or are otherwise different.	Medium4	StringImplementation+1	No attempts yet	2s	512 MB	Judgeable
Forbidden ZeroGiven a positive integer n with no digit 0, find the next integer in increasing order that also contains no digit 0.	Medium4	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Filling an Arithmetic SequenceTwo terms of a ten-term arithmetic sequence are given at unknown positions; fill in the rest with integers or report that no integer completion exists.	Medium4	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Police StationIn a directed graph, list every vertex from which all other vertices are reachable by following arrows forward.	Medium4	GraphDFS+1	No attempts yet	2s	1024 MB	Judgeable
Wet Rock Peg PlanSimulate a sequence of peg placements and removals on a dependency DAG, tracking peak peg count and the first wet-rule violation.	Medium4	SimulationGraph+2	No attempts yet	2s	512 MB	Judgeable
Olympiad PizzaContestants queue for pizza slices; each takes one slice per turn and rejoins the back if still hungry. Report the second each finishes.	Medium4	QueueSimulation+2	No attempts yet	2s	512 MB	Judgeable
Frosh WeekGiven task durations and quiet-interval lengths, each between 100000 and 199999, pair tasks with intervals that fit them and maximize the number of completed tasks.	Medium4	GreedyTwo pointers+2	No attempts yet	4s	512 MB	Judgeable
ZigZagGiven K words and N letters, output for each letter the word starting with it that has been used fewest times, breaking ties alphabetically.	Medium4	SortingHash map+2	No attempts yet	2s	64 MB	Judgeable
Street LightsGiven existing street lights that each cover K metres to both sides, find the minimum number of extra lights needed to light every metre from 1 to N.	Medium4	GreedySorting+2	No attempts yet	1s	64 MB	Judgeable
How to Eat at a BuffetGiven a plate area and items with value per area and available area, pick fractions to maximize total value on the plate.	Medium4	GreedySorting	No attempts yet	2s	512 MB	Judgeable
Frosting on the CakeGiven vertical stripe widths A and horizontal stripe heights B, find the total area of each of the three colors where each cell's color is (i+j) mod 3.	Medium4	ArrayMath+2	No attempts yet	5s	512 MB	Judgeable
GlitchBotFind which single instruction in a list of Left, Right, and Forward must be changed, and to what, so the robot ends at the given target.	Medium4	SimulationBrute force+1	No attempts yet	2s	512 MB	Judgeable
Wizard of OddsGiven N possible secret numbers and K yes/no questions, decide whether K adaptive questions always identify the number, where K questions distinguish at most 2^K outcomes.	Medium4	MathBinary search+2	No attempts yet	2s	512 MB	Judgeable
Treasure HuntFollow a grid of arrows from the top-left cell and report the number of steps to the treasure, Out if you leave the grid, or Lost if you loop forever.	Medium4	SimulationGraph+2	No attempts yet	2s	512 MB	Judgeable
The Bovine ShuffleGiven a permutation describing one shuffle and the cow order after three shuffles, recover the original order before the shuffles.	Medium4	ArrayImplementation+2	No attempts yet	2s	512 MB	Judgeable
Milk MeasurementThree cows start at 7 gallons; apply N dated changes in chronological order and count the days on which the set of cows holding the top output changes.	Medium4	SimulationSorting+2	No attempts yet	2s	512 MB	Judgeable
Coloring IntervalsGiven n closed intervals with distinct endpoints, find the minimum number of colors so that overlapping intervals get different colors.	Medium4	SortingIntervals+2	No attempts yet	3s	512 MB	Judgeable
WindowGiven N panes of size W by H, slide odd-indexed panes east and even-indexed panes west by given distances, then compute the uncovered window area.	Medium4	ArraySimulation+2	No attempts yet	2s	512 MB	Judgeable
Best Matched PairGiven up to 1000 distinct integers, find the largest product of two whose product's decimal digits form a consecutive increasing run like 123; print -1 if none exists.	Medium4	ImplementationBrute force+2	No attempts yet	2s	512 MB	Judgeable
N and M (7)Given N distinct numbers and a length M, print every length-M sequence drawn from the numbers with repetition allowed, deduplicated and in increasing lexicographic order.	Medium4	BacktrackingRecursion+2	No attempts yet	1s	512 MB	Judgeable
N and M (9)Given N numbers (with duplicates) and length M, print every distinct length-M selection in increasing lexicographic order, using each copy at most once.	Medium4	BacktrackingSorting+1	No attempts yet	1s	512 MB	Judgeable
N and M (11)Given N numbers and a length M, list every length-M sequence drawn from the numbers, allowing repeats, in increasing lexicographic order without duplicates.	Medium4	BacktrackingRecursion+2	No attempts yet	1s	512 MB	Judgeable
N and M (12)Given N numbers and a length M, list all non-decreasing length-M sequences drawn from the numbers with repetition, in lexicographic order.	Medium4	BacktrackingSorting+2	No attempts yet	2s	512 MB	Judgeable
OthelloGiven the sequence of moves of a valid 6x6 Othello game, replays them and prints the final board plus the winner.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Word Search in a GridDecide whether a word appears in a grid along a straight line of neighboring cells in any of the eight directions.	Medium4	ArraySimulation+2	No attempts yet	2s	512 MB	Judgeable
N-Step SyllogismEach premise says all a are b; for each conclusion x is y, decide whether following the implication chain from x reaches y.	Medium4	GraphDFS+2	No attempts yet	2s	128 MB	Judgeable
JujisuGiven an N by M grid of populations, answer K queries for the sum of people inside each requested rectangle.	Medium4	Prefix sumArray+2	No attempts yet	2s	512 MB	Judgeable
Counting equilateral trianglesGiven a triangular tower with N layers of unit triangles, count every equilateral triangle of any size, both upward and downward pointing.	Medium4	MathCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Big Integer A+BRead two integers up to 10^10000 in magnitude and print their sum without using built-in big integer support.	Medium4	ImplementationString+2	No attempts yet	1s	512 MB	Judgeable
HoofballSort cows by position, then find the minimum number of starting balls so every cow receives the ball at least once under the nearest-cow passing rule.	Medium4	SortingGraph+1	No attempts yet	2s	512 MB	Judgeable
Taming the HerdGiven a partial daily log of days-since-breakout values with a breakout on day 1, find the minimum and maximum possible breakouts.	Medium4	GreedyArray+2	No attempts yet	2s	512 MB	Judgeable
Lemonade LineGiven each cow's maximum tolerated queue length, choose an arrival order that minimizes how many cows end up waiting in line.	Medium4	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
SegmentationTrack visits per user over time and answer queries by mapping each user's recency and frequency to one of 12 RF segments.	Medium4	Hash mapImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Balance StoneOne cell of an N by N grid is 0; find the number M that makes all rows, columns, and both diagonals share one common sum, or print -1.	Medium4	ImplementationMath+1	No attempts yet	1s	512 MB	Judgeable
Aku NegarakuFor each N and M, simulate Josephus elimination around a circle and report the last remaining trainee's number.	Medium4	SimulationArray+1	No attempts yet	3s	512 MB	Judgeable
Binary CountingGenerate the binary representation of each non-negative integer in order, concatenate the digits, and print every n-th digit starting at position k (five of them).	Medium4	ImplementationMath+2	No attempts yet	1s	32 MB	Judgeable
Au au ua ui ya!!Given N segments [x, y] already sorted by x, compute the total length covered by their union on the number line.	Medium4	IntervalsSorting+2	No attempts yet	2s	512 MB	Judgeable