Interview warm-up

Short whiteboard warmups

Under construction

Still being built. Things may change

Total results4,880 problems

Hospital
Medium4
Tree, DFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Easy Word
Medium4
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cars in Byteland
Medium4
Queue, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Championship
Medium4
Sorting, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Saruman
Medium4
Prefix sum, Binary search
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Elven Pyramid
Medium4
Array, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sewer
Medium4
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Catching the Hulk
Medium4
Geometry, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Typewriter
Medium4
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Curse of the Black Pearl
Medium4
String, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Harry Potter and the Sorting Hat
Medium4
Bit manipulation, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Moose Calf
Medium4
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fence Painting
Medium4
Array, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Lambda
Medium4
Tree, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sums of Blue and Red Cubes
Medium4
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tail of a Graph
Medium4
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Paper Cups
Medium4
Heap, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
XOR
Medium4
Trie, Bit manipulation
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Triangular Key
Medium4
Implementation, Matrix
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Keep the ranks - 2
Medium4
Greedy, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hold the line - 3
Medium4
Prefix sum, Sliding window+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gagarin Cup
Medium4
Probability, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Backup System
Medium4
Simulation, Stack+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Martian Friend
Medium4
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Journey
Medium4
Greedy, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Super Massive Black Hole
Medium4
Sorting, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Playlist
Medium4
Dynamic programming, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Roads
Medium4
Shortest path, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Card Trick
Medium4
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Chemical Cipher
Medium4
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Glue!
Medium4
BFS, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tree
Medium4
Tree, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Wipe it!
Medium4
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Brick towers
Medium4
Prefix sum, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cubes
Medium4
String, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Most Global Positioning System
Medium4
Geometry, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Diligent Beavers
Medium4
Graph, BFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Art Class
Medium4
Union-find, Array
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Football Formation
Medium4
Brute force, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Festive Olympiad
Medium4
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Big Horse Race
Medium4
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Advertising Poster
Medium4
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Songi in the Strange Hotel
Medium4
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Last-minute cramming
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Amidakuji
Medium4
Brute force, Simulation+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Beusi's marble ice cream
Medium4
Hash map, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Slime Hunt and Level Up!
Medium4
Math, Binary search
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rick-Roll Virus
Medium4
Greedy, Intervals
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Black Holes and Asteroids
Medium4
Sorting, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
DDR Stamina Management
Medium4
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Drawing a Tree
Medium4
Sorting, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Square Root Sequence
Medium4
Dynamic programming, Prefix sum
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Palindrome Name
Medium4
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Coloring by Numbers
Medium4
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Illumination Optimization
Medium4
Greedy, Intervals
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
ASCII Art
Medium4
Math, Binary search
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
I Don't Want to Be Late
Medium4
Segment tree, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Turning Pencils
Medium4
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Prizes
Medium4
Array, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Carrying the Bags
Medium4
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rumors
Medium4
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Air Leak
Medium4
Graph, BFS
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Racing Strategy
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fence Painting
Medium4
Sorting, Intervals+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Strange Machine
Medium4
Dynamic programming, Simulation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Gift Bag
Medium4
Hash map, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Machine Shop
Medium4
Dynamic programming, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Superknight
Medium4
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Voltage Drops
Medium4
Union-find, Graph
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lining up Children
Medium4
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Martian Calendar
Medium4
Math, Binary search+1
No attempts yet
Time limit
0.2s
Memory limit
1024 MB
Judgeable
Medals
Medium4
Array, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dolbear's Law
Medium4
Brute force, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Junyoung's Love
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Picking the Student Council
Medium4
Bit manipulation, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cornfield
Medium4
Heap, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Multiples of K
Medium4
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
HJS
Medium4
Brute force, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Distance Keeping Game
Medium4
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Snow-covered path
Medium4
Prefix sum, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
YouTube
Medium4
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Karosai
Medium4
Minimum spanning tree, Union-find+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Change
Medium4
Greedy, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bicycle Track Race
Medium4
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Most Important Bridge
Medium4
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Interview Room of Terror
Medium4
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Make a New String
Medium4
String, String matching
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
So I Quit Photography
Medium4
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Educational Tree Problem
Medium4
Sorting, Tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Compass
Medium4
Graph, Geometry+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Playing Field
Medium4
Prefix sum, Geometry+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Crazy Malvika discovers Crazy Fibonacci function
Medium4
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Squared Weighted Sums
Medium4
Prefix sum, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Novel
Medium4
String, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bicycle
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Vehicle Placement
Medium4
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
April Fools
Medium4
Brute force, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Weighted Window Sums
Medium4
Prefix sum, Sorting
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Union
Medium4
Brute force, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candy Split
Medium4
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
HospitalFind a vertex of a weighted tree whose removal leaves components with the smallest possible maximum total population.	Medium4	TreeDFS	No attempts yet	2s	1024 MB	Judgeable
Easy WordGiven a word, find the minimal complexity among its distinct cyclic shifts and how many shifts reach that minimum.	Medium4	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Cars in BytelandModels enter and leave a production queue, and for each query the task asks how many models are priced exactly at the current mean price.	Medium4	QueueHash map+1	No attempts yet	2s	1024 MB	Judgeable
ChampionshipGiven N team names, output the team numbers in the table order that makes the concatenated name string lexicographically smallest.	Medium4	SortingString	No attempts yet	2s	1024 MB	Judgeable
SarumanGiven a non-decreasing array, for each query (length l, sum s) find the start of a contiguous block of l regiments whose total equals s, or report -1.	Medium4	Prefix sumBinary search	No attempts yet	2s	1024 MB	Judgeable
Elven PyramidGiven stacked rings with inner and outer radii, list the rings that must come off before the bottom ring can be removed.	Medium4	ArrayGreedy	No attempts yet	2s	1024 MB	Judgeable
SewerGiven a tree of n manholes and m queries, report the first manhole on the path from l to r for each query.	Medium4	TreeDFS+1	No attempts yet	2s	1024 MB	Judgeable
Catching the HulkGiven a box with a smaller box inside it in 1 to 3 dimensions, find the fewest cuts that leave only the inner box.	Medium4	GeometryImplementation	No attempts yet	2s	1024 MB	Judgeable
TypewriterGiven n words, one per line, find the fewest button presses to type them, where the copy key can reuse the previous line's word.	Medium4	StringGreedy+1	No attempts yet	2s	1024 MB	Judgeable
The Curse of the Black PearlCount the substrings of a string with '?' gaps that can be filled so every character is the same letter.	Medium4	StringTwo pointers+1	No attempts yet	1s	1024 MB	Judgeable
Harry Potter and the Sorting HatGiven n and p, find the house of the n-th student, where the house is the number of 1 bits in n-1 taken modulo p.	Medium4	Bit manipulationMath	No attempts yet	2s	1024 MB	Judgeable
Moose CalfFind the path through all N rows whose largest gap between neighboring trees is as small as possible, or report -1 if no path exists.	Medium4	GraphShortest path+1	No attempts yet	2s	1024 MB	Judgeable
Fence PaintingPick one target color for the fence so that repainting every run of non-target boards, at most s per day, takes the fewest days.	Medium4	ArrayImplementation	No attempts yet	2s	1024 MB	Judgeable
LambdaGiven pairs of tubers in a tree whose edges follow a fixed numbering rule, find the smallest tuber number on the path between each pair.	Medium4	TreeImplementation	No attempts yet	1s	1024 MB	Judgeable
Sums of Blue and Red CubesCount the pairs (x, y) with x and y each taken from the integers a to b whose sum lies between c and d inclusive.	Medium4	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Tail of a GraphGiven a connected undirected graph, find the number of vertices in the longest tail, a path whose inner vertices have no neighbors outside the path.	Medium4	GraphBFS+1	No attempts yet	2s	1024 MB	Judgeable
Paper CupsGiven n cups with leftover drink amounts, nonempty cups start new stacks and empty cups join the smallest stack; print the largest stack height.	Medium4	HeapGreedy+1	No attempts yet	1s	1024 MB	Judgeable
XORFor each b_j, find the a_k from the given set that maximizes a_k XOR b_j, with up to 100,000 values in each list.	Medium4	TrieBit manipulation	No attempts yet	4s	1024 MB	Judgeable
Triangular KeyRotate a triangular grid of digits 90 degrees in the given direction and print the result in the same triangular format.	Medium4	ImplementationMatrix	No attempts yet	2s	1024 MB	Judgeable
Keep the ranks - 2Given n and k, print a permutation of 1 to n that has exactly k inversions, where an inversion is a pair with the larger value placed first.	Medium4	GreedyArray+1	No attempts yet	2s	1024 MB	Judgeable
Hold the line - 3Each soldier's index counts strictly shorter soldiers on both sides; output the leftmost start of a length-k window with the maximal index sum.	Medium4	Prefix sumSliding window+1	No attempts yet	2s	1024 MB	Judgeable
Gagarin CupGiven per-venue win probabilities for two teams in a first-to-four series with a 2-2-1-1-1 schedule, find the chance the series ends with a given score.	Medium4	ProbabilityDynamic programming	No attempts yet	2s	1024 MB	Judgeable
Backup SystemSimulate a backup system on a lowercase string: when a character repeats, output the suffix after its last occurrence as a backup, then print the final string.	Medium4	SimulationStack+1	No attempts yet	2s	1024 MB	Judgeable
Martian FriendGiven N and k, count how many trailing zeros N! has when written in base k.	Medium4	MathNumber theory	No attempts yet	2s	1024 MB	Judgeable
JourneyGiven taken seats and the seats Lida wants (out of 54), find the fewest ticket ranges that buy every wanted seat without buying any unwanted free seat.	Medium4	GreedyImplementation	No attempts yet	2s	1024 MB	Judgeable
Super Massive Black HoleGiven n black holes with masses w_i and a deadline D, find the minimum total cost to produce one per day and move each to day D.	Medium4	SortingDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
PlaylistDecide whether the first song can be playing at second T when the shuffle plays every song once per round in random order.	Medium4	Dynamic programmingImplementation	No attempts yet	2s	1024 MB	Judgeable
RoadsGiven unit roads on an integer grid, find the fewest new unit roads that make the mayor's home-to-city-hall trip as short as possible.	Medium4	Shortest pathBFS+1	No attempts yet	2s	1024 MB	Judgeable
Card TrickGiven n and m, find the minimum number of deals that always brings the chosen card to the top, which equals the count of base-m digits of n-1.	Medium4	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Chemical CipherGiven a cipher string and a list of element symbols, find the fewest symbols whose concatenation contains the cipher as a subsequence, or -1 if none exists.	Medium4	Dynamic programmingGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Glue!Given a grid of piece labels, check that every label covers exactly k cells and that each piece is connected through shared sides.	Medium4	BFSHash map+1	No attempts yet	2s	1024 MB	Judgeable
TreeCount the red and green colorings of a rooted tree's edges where each vertex has at most one red edge from its children, modulo 10^9 + 7.	Medium4	TreeDynamic programming	No attempts yet	2s	1024 MB	Judgeable
Wipe it!Simulate a teacher writing a word one letter at a time, wiping each suffix that already appears elsewhere in the word, and output the final word on the board.	Medium4	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Brick towersGiven n tower heights and a target k, find the longest run of consecutive towers whose average height is exactly k, and output its length and start index.	Medium4	Prefix sumHash map+1	No attempts yet	2s	1024 MB	Judgeable
CubesGiven strings of A and B cubes, decide whether each line can be split into single A cubes and adjacent AB or BA bricks.	Medium4	StringGreedy	No attempts yet	2s	1024 MB	Judgeable
The Most Global Positioning SystemGiven three non-collinear tower positions and the distance from each tower to an object, find the object's coordinates, or print Impossible if no point fits.	Medium4	GeometryMath	No attempts yet	2s	1024 MB	Judgeable
Diligent BeaversGiven ten rules for a beaver moving along an infinite row of trees, decide whether the beaver can become happy starting from the angry mood.	Medium4	GraphBFS	No attempts yet	2s	1024 MB	Judgeable
Art ClassGiven N cells and Q range queries that paint only still-uncolored cells, print the final color of each cell.	Medium4	Union-findArray	No attempts yet	0.5s	512 MB	Judgeable
Football FormationGiven ten player positions, find all formations the team could have had, where at most two players move between each pair of lines.	Medium4	Brute forceImplementation	No attempts yet	2s	1024 MB	Judgeable
Festive OlympiadGiven n problems with solve times and m teams that work in parallel, find the minimum sum of submission times for all problems.	Medium4	GreedySorting	No attempts yet	2s	1024 MB	Judgeable
Big Horse RaceGiven a line through two points and N circles, find the total length of the line covered by at least one circle.	Medium4	GeometrySorting+1	No attempts yet	2s	1024 MB	Judgeable
Advertising PosterEach word of a slogan is placed horizontally or vertically, with no two vertical words in a row, to minimize the longest horizontal word.	Medium4	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
Songi in the Strange HotelGiven the rank N of a room when all room labels are sorted, print the labels of the rooms on the path from that room up to room 1 on floor 1.	Medium4	MathImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Last-minute crammingChoose which problems to solve within T days so that the total fine of the unsolved problems is as small as possible.	Medium4	Dynamic programming	No attempts yet	1s	1024 MB	Judgeable
AmidakujiGiven an amidakuji and a start line p, find the position of one added bar that routes p's trace to line q, or report OK or NG.	Medium4	Brute forceSimulation+1	No attempts yet	8s	1024 MB	Judgeable
Beusi's marble ice creamApply Q steps to a multiset of marbles: each step removes A_i and adds B_i only when every marble in A_i is present, then print what remains.	Medium4	Hash mapImplementation	No attempts yet	1s	1024 MB	Judgeable
Slime Hunt and Level Up!After N slimes, where the k-th slime gives k experience and each level-up costs 2 more than the last, find the level Bsil reaches.	Medium4	MathBinary search	No attempts yet	1s	1024 MB	Judgeable
Rick-Roll VirusGiven a line of N people with infected ones marked R, decide whether M cures can stop the virus that spreads K cells per day.	Medium4	GreedyIntervals	No attempts yet	2s	1024 MB	Judgeable
Black Holes and AsteroidsGiven black hole and asteroid positions, find the smallest integer P so that every asteroid is within P/w of some black hole.	Medium4	SortingBinary search+1	No attempts yet	1s	1024 MB	Judgeable
DDR Stamina ManagementChoose which sections to play so total points are maximized, where stamina recovers by K before each section (capped at 100) and playing costs h_i stamina.	Medium4	Dynamic programmingImplementation	No attempts yet	1s	1024 MB	Judgeable
Drawing a TreeConnect N given points with N-1 segments that form a tree and do not cross, then print the endpoint index pairs.	Medium4	SortingImplementation	No attempts yet	1s	1024 MB	Judgeable
Square Root SequenceCount the sequences of length L that start at N, end at 1, and where each term is less than the square root of the term before it.	Medium4	Dynamic programmingPrefix sum	No attempts yet	1s	1024 MB	Judgeable
Palindrome NameBuild a string of length N using exactly K distinct lowercase letters that has the most distinct palindromic substrings, choosing the lexicographically smallest on ties.	Medium4	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
Coloring by NumbersGiven a 1 x W grid and N blocks placed in order with at least one gap between them, find every cell colored in all valid placements.	Medium4	GreedyIntervals+1	No attempts yet	1s	1024 MB	Judgeable
Illumination OptimizationGiven M, R, and sorted street light positions, find the fewest bulbs whose lit segments cover the whole freeway from 0 to M, or report IMPOSSIBLE.	Medium4	GreedyIntervals	No attempts yet	10s	1024 MB	Judgeable
ASCII ArtGiven N, find the N-th character printed by a program that prints each letter A to Z i times in round i, for i from 1 upward.	Medium4	MathBinary search	No attempts yet	20s	1024 MB	Judgeable
I Don't Want to Be LateGiven route populations under point updates, report the first and second route numbers of a fastest Aeji Hall to ITBT path, breaking ties by smallest index.	Medium4	Segment treeArray	No attempts yet	1s	1024 MB	Judgeable
Turning PencilsGiven N pencils, each pointing sharp end up or blunt end up, find the fewest segment flips that make all pencils face the same way and print those flips.	Medium4	GreedyString+1	No attempts yet	1s	1024 MB	Judgeable
PrizesGiven N prize prices and a budget K, determine whether three different prizes have prices that sum to exactly K.	Medium4	ArraySorting+1	No attempts yet	1s	1024 MB	Judgeable
Carrying the BagsGiven K bags, a walking time X, and a per-bag delay Y, find the trip plan that moves all bags to the award table in the least total time.	Medium4	Dynamic programmingMath	No attempts yet	1s	1024 MB	Judgeable
RumorsFor each rumor originator, count how many students hear it when every listener repeats it to all of their social circles.	Medium4	GraphBFS+1	No attempts yet	1s	1024 MB	Judgeable
Air LeakGiven the open doors between modules in a 25x25x25 grid, find every module that air can flow to from the damaged module.	Medium4	GraphBFS	No attempts yet	1s	1024 MB	Judgeable
Racing StrategyPick a starting tyre and pit stops over N laps so the total race time is minimal, given each tyre's first-lap time, per-lap wear, and a fixed pit cost K.	Medium4	Dynamic programming	No attempts yet	1s	1024 MB	Judgeable
Fence PaintingGiven painted house numbers and a distance K, list the unpainted houses within K of a painted house, merging consecutive runs as a..b.	Medium4	SortingIntervals+1	No attempts yet	1s	1024 MB	Judgeable
Strange MachineGiven a button press sequence where some presses are unknown (-1), find which of the four bulbs can be lit after the last press.	Medium4	Dynamic programmingSimulation	No attempts yet	3s	1024 MB	Judgeable
Gift BagGiven item prices and a gift list, find the lowest total cost after swapping the prices of at most one pair of items.	Medium4	Hash mapBrute force	No attempts yet	1s	1024 MB	Judgeable
Machine ShopFind the lowest cost of obtaining machine K, either by buying it outright or by building it from its component machines, each obtained at its own lowest cost.	Medium4	Dynamic programmingGraph+1	No attempts yet	1s	1024 MB	Judgeable
SuperknightFind the fewest moves for a knight on an R by V board with blocked squares, where one move may be a 3-by-1 supermove, and print one shortest path.	Medium4	BFSGraph+1	No attempts yet	1s	1024 MB	Judgeable
Voltage DropsGiven voltage differences between pairs of nodes, decide whether all measurements can be consistent with one set of node potentials, printing JAH or EI.	Medium4	Union-findGraph	No attempts yet	1s	1024 MB	Judgeable
Lining up ChildrenGiven friend pairs among N children, find a line order where every friend pair stands next to each other, or report that no such order exists.	Medium4	GraphUnion-find+1	No attempts yet	1s	1024 MB	Judgeable
Martian CalendarFind the sum of each day's position within its month for all days from the A-th to the B-th day of the year, where month m has m days.	Medium4	MathBinary search+1	No attempts yet	0.2s	1024 MB	Judgeable
MedalsGiven medal numbers from several series, split them into the fewest runs of consecutive competition numbers and report the run count.	Medium4	ArrayGreedy	No attempts yet	2s	1024 MB	Judgeable
Dolbear's LawGiven a per-second record of chirps, find the fewest crickets that could explain it when each cricket chirps at a fixed period between a start and a stop.	Medium4	Brute forceImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Junyoung's LoveRearrange N pearl values in a circle to maximize the sum of products of adjacent pearls, then print the maximum and one arrangement that reaches it.	Medium4	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Picking the Student CouncilPick K of N integers so that their bitwise AND is as large as possible, and print that maximum value.	Medium4	Bit manipulationGreedy	No attempts yet	1s	1024 MB	Judgeable
CornfieldGiven a grid of distinct values, repeatedly harvest the largest-valued cell reachable from the border through already harvested cells, and print the first K positions in order.	Medium4	HeapGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Multiples of KCount the M-digit numbers made only from the given digits that are multiples of K, modulo 1,000,000,007.	Medium4	Dynamic programmingMath	No attempts yet	1s	1024 MB	Judgeable
HJSGiven three H/J/S patterns of equal length, check whether distinct digits 1 to 9 can be assigned to H, J, and S so that the numbers satisfy p < q < r.	Medium4	Brute forceImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Distance Keeping GameGiven an N x M grid and a distance D, count the cells whose farthest grid cell is still closer than D in taxicab distance, since Hyoseok must block exactly those.	Medium4	MathBrute force	No attempts yet	1s	1024 MB	Judgeable
Snow-covered pathGiven the snow depth on each meter of a path, find the total energy spent when each thrown load of snow adds a 1 cm layer to the meters ahead.	Medium4	Prefix sumSimulation	No attempts yet	1s	1024 MB	Judgeable
YouTubePick videos with durations t_i and values of 1 or 2 to reach a total value of at least V with the least watch time, or print -1 if it is impossible.	Medium4	SortingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
KarosaiGiven ponds joined by partitions with fixed heights, find the minimum water level at pond 1 that allows a path to pond N.	Medium4	Minimum spanning treeUnion-find+1	No attempts yet	1s	1024 MB	Judgeable
ChangeFor each change request, output the fewest bit banknotes from the register's stock, listed from largest to smallest denomination.	Medium4	GreedyImplementation	No attempts yet	1s	1024 MB	Judgeable
Bicycle Track RaceGiven each racer's time per lap and the race length in laps, count the racers who are never lapped and finish the race.	Medium4	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
The Most Important BridgeFind the bridge whose removal splits the 2N islands into two disconnected groups of exactly N islands each, and print its number.	Medium4	GraphDFS+1	No attempts yet	1s	1024 MB	Judgeable
Interview Room of TerrorInterviews run one at a time. Find the minimum sum of the finish times of all departments, given each department's total interview time.	Medium4	GreedySorting	No attempts yet	1s	1024 MB	Judgeable
Make a New StringGiven each string S, build the shortest X that starts with S and whose reverse also starts with S.	Medium4	StringString matching	No attempts yet	1s	1024 MB	Judgeable
So I Quit PhotographyFind the minimum and maximum photo score over all orderings of N students, how many orderings reach each, and one example of each.	Medium4	SortingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Educational Tree ProblemGiven a rooted tree where each child's value is at most its parent's, find the maximum sum of a parent-closed vertex set for each size k from 1 to N.	Medium4	SortingTree+1	No attempts yet	1s	1024 MB	Judgeable
CompassCount the circles from which a chain of pairwise intersecting or touching circles reaches the sheet edge, given the sheet size and N circles.	Medium4	GraphGeometry+1	No attempts yet	1s	1024 MB	Judgeable
Playing FieldGiven a convex polygon and several diagonals, find the area of the smaller piece that each diagonal cuts off.	Medium4	Prefix sumGeometry+2	No attempts yet	2s	1024 MB	Judgeable
Crazy Malvika discovers Crazy Fibonacci functionGiven f(1)=A, f(2)=B, and f(x)=f(x-1)+f(x+1), find f(N) modulo 10^9+7 for up to 10^5 queries.	Medium4	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Squared Weighted SumsGiven N integers, print for each k the sum of (k-i)^2 times a_i over the first k elements, for k from 1 to N.	Medium4	Prefix sumMath	No attempts yet	1s	1024 MB	Judgeable
NovelFind the largest line width L so that no K identical lowercase letters appear consecutively within a single line of the string.	Medium4	StringImplementation+1	No attempts yet	1s	1024 MB	Judgeable
BicycleGiven morning and evening rain forecasts for N days, find the maximum number of days Aleksas can ride his bike, tracking whether the bike is at home or at work.	Medium4	Dynamic programming	No attempts yet	1s	1024 MB	Judgeable
Vehicle PlacementCount the vehicle placements on a road graph where no two vehicles reach location 1 at the same time, modulo 1000000007.	Medium4	BFSGraph+1	No attempts yet	1s	1024 MB	Judgeable
April FoolsEach newspaper prints exactly one false fact. Find the smallest and largest total number of false facts that can be consistent with this.	Medium4	Brute forceBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Weighted Window SumsGiven a sequence and window size k, list each window's start index and weighted sum (1a1 + 2a2 + ...), sorted by sum with ties broken by start index.	Medium4	Prefix sumSorting	No attempts yet	5s	1024 MB	Judgeable
UnionGiven n sets of positive integers, find the largest union of some of them that differs from the union of all sets.	Medium4	Brute forceBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
Candy SplitChoose a set of candy boxes whose total is even and as large as possible, then print half of that total.	Medium4	Dynamic programmingArray+1	No attempts yet	1s	1024 MB	Judgeable