Problems

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Total results21,595 problems

Paris by NightHard8
Geometry, Sorting +2No attempts yetTime limit15sMemory limit512 MB
Judgeable
Travel GuideHard8
Shortest path, Graph +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
Dishonest DriverHard8
Dynamic programming, String +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
Balance ScaleHard8
Math, Hash map +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Running RoutesHard8
Dynamic programming, Intervals +2No attempts yetTime limit12sMemory limit1024 MB
Judgeable
Stop Counting!Hard8
Math, Prefix sum +2No attempts yetTime limit7sMemory limit1024 MB
Judgeable
Sequence and Queries 31Hard8
Segment tree, Intervals +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Shopping MallHard8
Simulation, Heap +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Frog JumpHard8
Geometry, Union-find +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
DroneHard8
BFS, Shortest path +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
BracketsHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Black StonesHard8
Tree, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
XORangesHard8
Bit manipulation, Segment tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Strange MachineHard8
Math, Number theory +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
SeparatorHard8
Tree, Implementation +2No attempts yetTime limit1.2sMemory limit512 MB
Judgeable
Sum of Squares 2 (More Huge)Hard8
Math, Number theory +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
NamuhsHard8
Divide and conquer, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ResistanceHard8
Graph, Minimum spanning tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ExamHard8
Sorting, Prefix sum +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Cake 3Hard8
Dynamic programming, Greedy +2No attempts yetTime limit4sMemory limit256 MB
Judgeable
MineralsHard8
Divide and conquer, Implementation +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
TentsHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
LibraryHard8
Intervals, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
MatryoshkaHard8
Sorting, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
TelegraphHard8
Graph, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Copy and Paste 2Hard8
Implementation, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
JOI Logo DesignHard8
Dynamic programming, Divide and conquer +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
IOIOI CardsHard8
Shortest path, Graph +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
InheritanceHard8
Graph, Union-find +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
BusHard8
Graph, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Growing Vegetables is FunHard8
Greedy, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Making Friends is FunHard8
Graph, Union-find +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
ScarecrowsHard8
Sorting, Divide and conquer +1No attempts yetTime limit4sMemory limit512 MB
Judgeable
Collecting Images is FunHard8
Divide and conquer, Implementation +2No attempts yetTime limit5sMemory limit256 MB
Judgeable
MascotsHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
SpyHard8
Tree, DFS +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
White Day Present ExchangeHard8
Graph, Dynamic programming +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
EquationHard8
Math, Brute force +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ChampionshipsHard8
Graph, Implementation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
JOI FlagHard8
Divide and conquer, Dynamic programming +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Inquiry IIHard8
Tree, DFS +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Estate AgentHard8
Graph, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Grand Central StationHard8
Tree, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Hat StandHard8
Greedy, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Mosaic MansionHard8
Dynamic programming, Hash map +2No attempts yetTime limit12sMemory limit512 MB
Judgeable
DžumbusHard8
Dynamic programming, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Dice YutnoriHard8
Backtracking, Simulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Lion and RabbitHard8
Graph, BFS +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Fibonacci MusicHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Copy and PasteHard8
String, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cheese, If You PleaseHard8
Math, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Just Passing ThroughHard8
Dynamic programming, Matrix +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Where Have You Bin?Hard8
Dynamic programming, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Circle GardenHard8
Geometry, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Integers in Rational BasesHard8
Number theory, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
HogwartsHard8
Graph, BFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
MoleculesHard8
Graph, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Watch LaterHard8
Dynamic programming, Bit manipulation +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
Pairing SocksHard8
Stack, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Tree HuggingHard8
Graph, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Loo RollsHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Dice and LaddersHard8
Probability, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Counting Permutations with a Given Greedily Increasing SubsequenceHard8
Combinatorics, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Ranch CCTVHard8
Prefix sum, Matrix +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Pizza Grows as You Slice ItHard8
Math, Combinatorics +1No attempts yetTime limit1sMemory limit256 MB
Judgeable
Warm Pork GukbapHard8
Dynamic programming, Binary search +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Max or MinHard8
Implementation, Greedy +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
3D Points and QueriesHard8
Segment tree, Sorting +2No attempts yetTime limit7sMemory limit1024 MB
Judgeable
Game on a TreeHard8
Tree, Game theory +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Strike ZoneHard8
Dynamic programming, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
WasherHard8
Geometry, Divide and conquer +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Drive SafelyHard8
Dynamic programming, Geometry +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
EquilibriumHard8
Tree, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Great GDPHard8
Binary search, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Ice CreamHard8
Graph, Shortest path +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Computer CacheHard8
Segment tree, Array +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Fixed Point PermutationsHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Interstellar TravelHard8
Geometry, Math +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Jumping PathHard8
Dynamic programming, DFS +2No attempts yetTime limit10sMemory limit512 MB
Judgeable
Glow, Pixel, Glow!Hard8
Sorting, Implementation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cocoa CoalitionHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Building the Perfect HouseHard8
Geometry, Binary search +2No attempts yetTime limit1.5sMemory limit512 MB
Judgeable
Cut Inequality DownHard8
Segment tree, Implementation +2No attempts yetTime limit0.7sMemory limit512 MB
Judgeable
Dazzling StarsHard8
Geometry, Sorting +2No attempts yetTime limit0.2sMemory limit512 MB
Judgeable
Hold or Continue?Hard8
Dynamic programming, Probability +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Game of Falling BlocksHard8
Simulation, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Gnoll HypothesisHard8
Probability, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
PopcountHard8
Bit manipulation, Divide and conquer +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
ICPCHard8
Combinatorics, String matching +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Great Farmer Kim SanghyukHard8
Geometry, Math +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Optimal SelectionHard8
Divide and conquer, Game theory +2No attempts yetTime limit8sMemory limit1024 MB
Judgeable
Zeldain GardenHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Light Emitting HindenburgHard8
Bit manipulation, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
K==SHard8
String matching, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
True/False WorksheetHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Ambiguous EncodingHard8
String matching, BFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sink the Billiard BallHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Who Has Not Read the Message?Hard8
Combinatorics, Dynamic programming +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Water Tanks of Seongdae CountryHard8
Tree, DFS +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Shortest Paths and QueriesHard8
Dynamic programming, Matrix +2No attempts yetTime limit5sMemory limit512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Paris by NightGiven N graded points in general position, pick two boundary monuments and split the rest by the line through them to minimize the absolute difference of the two side sums.	Hard8	GeometrySorting+2	No attempts yet	15s	512 MB	Judgeable
Travel GuideGiven a weighted undirected graph with three special nodes, count the vertices that are not dominated in all three distances by another vertex.	Hard8	Shortest pathGraph+2	No attempts yet	6s	512 MB	Judgeable
Dishonest DriverGiven a string of N characters, find the size of the shortest compressed form built from single characters, concatenation, and repetition (C repeated k times).	Hard8	Dynamic programmingString+2	No attempts yet	6s	512 MB	Judgeable
Balance ScaleGiven a set of existing weights and target amounts, find the lightest single new weight that makes every amount expressible as a signed subset sum of the weights, or report 0 or -1.	Hard8	MathHash map+2	No attempts yet	2s	512 MB	Judgeable
Running RoutesGiven chords of a convex n-gon, find the largest set of chords no two of which share any common point, including endpoints.	Hard8	Dynamic programmingIntervals+2	No attempts yet	12s	1024 MB	Judgeable
Stop Counting!Given a deck of integers, choose one contiguous block to skip so the average of the remaining cards is maximized.	Hard8	MathPrefix sum+2	No attempts yet	7s	1024 MB	Judgeable
Sequence and Queries 31Maintain a 0/1 sequence under range reversals, and answer queries for the longest run of 1s inside a given range.	Hard8	Segment treeIntervals+2	No attempts yet	2s	512 MB	Judgeable
Shopping MallSimulate customers choosing the counter with the minimum total wait (lowest index on ties), then compute a weighted sum of membership numbers in the order customers leave.	Hard8	SimulationHeap+2	No attempts yet	1s	512 MB	Judgeable
Frog JumpGiven N disjoint horizontal line segments, two logs are connected if a vertical jump between them crosses no other log; answer queries on whether logs are reachable.	Hard8	GeometryUnion-find+1	No attempts yet	1s	512 MB	Judgeable
DroneA drone moves on an N x N tile maze with walls; LED tiles light up in sequence order as the drone steps on them, and we need the shortest total travel time to display the whole sequence and exit.	Hard8	BFSShortest path+2	No attempts yet	1s	512 MB	Judgeable
BracketsFor each N, find the valid bracket string with bracket value N whose digit-encoded decimal value is smallest, and print it.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Black StonesGiven a tree with some vertices marked black, count how many queries (i, j) admit a connected subtree with exactly i vertices and j black vertices.	Hard8	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
XORangesMaintain an array under point updates and answer queries for the XOR of every contiguous subarray inside [l, u].	Hard8	Bit manipulationSegment tree+2	No attempts yet	1s	512 MB	Judgeable
Strange MachineCount the distinct pairs (x, y) produced by the map t -> (((t + floor(t/B)) mod A), t mod B) over n disjoint time intervals.	Hard8	MathNumber theory+2	No attempts yet	4s	512 MB	Judgeable
SeparatorAppend values one at a time to a growing sequence and after each append report how many indices are separators, meaning every earlier element is smaller and every later element is larger.	Hard8	TreeImplementation+2	No attempts yet	1.2s	512 MB	Judgeable
Sum of Squares 2 (More Huge)Given n up to 10^18, find the minimum number of perfect squares summing to n and output the actual square roots used.	Hard8	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
NamuhsGiven N unknown planet potentials, find the unique contiguous segment with the maximum sum using only queries that compare the sums of two segments.	Hard8	Divide and conquerBinary search+2	No attempts yet	2s	512 MB	Judgeable
ResistancePlayers leave and return over time; after each change report the maximum value of a split into two teams, where friendship edges crossing the split are lost.	Hard8	GraphMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
ExamFor each of Q threshold triples, count students with S>=X, T>=Y, and S+T>=Z, where N and Q reach 100000.	Hard8	SortingPrefix sum+2	No attempts yet	3s	1024 MB	Judgeable
Cake 3Choose M of N slices and arrange them in a cycle to maximize total value minus the sum of absolute color-depth differences around the cycle.	Hard8	Dynamic programmingGreedy+2	No attempts yet	4s	256 MB	Judgeable
MineralsGiven 2N slices forming N unknown pairs, determine all pairs using at most 1,000,000 device operations that report the number of distinct mineral kinds currently inserted.	Hard8	Divide and conquerImplementation+2	No attempts yet	1s	256 MB	Judgeable
TentsCount nonempty subsets of tents on an H by W grid with directions obeying monotone entrance rules in every row and column, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
LibraryGiven a hidden permutation of N books, query the oracle with a set of book numbers and receive the minimum number of contiguous-block removals needed to extract exactly those books, then recover the order.	Hard8	IntervalsMath+2	No attempts yet	2s	512 MB	Judgeable
MatryoshkaFor each query (A, B), take the dolls with R >= A and H <= B and find the minimum number of chains needed to store them all nested, i.e. the size of the largest antichain under the containment partial order.	Hard8	SortingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
TelegraphEach island's receiver points to one other island; turning it costs C_i. Find the minimum total cost so that every island can reach every other in the resulting functional graph.	Hard8	GraphGreedy+2	No attempts yet	1s	512 MB	Judgeable
Copy and Paste 2Simulate N copy-and-paste edits on a string capped at length M, tracking positions backward so the first K characters of the final string can be printed.	Hard8	ImplementationBinary search+2	No attempts yet	1s	512 MB	Judgeable
JOI Logo DesignGiven a circular string of length 4^K over {J,O,I}, find the rotation that minimizes mismatches with a level-K JOI sequence built by recursive quarter block replacement.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
IOIOI CardsGiven a row of I/O cards and interval flip operations with per-length costs, decide whether all cards can be turned face up and find the minimum total flip time.	Hard8	Shortest pathGraph+2	No attempts yet	1s	512 MB	Judgeable
InheritanceK children take turns picking the heaviest cycle-free set of edges from the graph, and we must report which child gets each edge or 0 if nobody does.	Hard8	GraphUnion-find+2	No attempts yet	1s	512 MB	Judgeable
BusGiven scheduled one-way buses with fixed departure and arrival times, compute for each query deadline L the latest time to leave stop 1 to reach stop N by L, or -1.	Hard8	GraphSorting+2	No attempts yet	1s	512 MB	Judgeable
Growing Vegetables is FunGiven N plants in a row, find the minimum adjacent swaps to arrange heights so every plant is a prefix maximum or a suffix maximum.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Making Friends is FunGiven a directed graph of ambassador arrows, repeatedly pick a mediator x and two countries p,q with arrows (x,p) and (x,q), then add (p,q) and (q,p); maximize final arrow count.	Hard8	GraphUnion-find+2	No attempts yet	1s	512 MB	Judgeable
ScarecrowsCount pairs of scarecrows that can be the SW and NE corners of an axis-aligned rectangle whose interior contains no other scarecrow.	Hard8	SortingDivide and conquer+1	No attempts yet	4s	512 MB	Judgeable
Collecting Images is FunStart with an all-white 2^N by 2^N grid; after each of Q row or column flips, report the size of the quadtree that represents the image.	Hard8	Divide and conquerImplementation+2	No attempts yet	5s	256 MB	Judgeable
MascotsCount the orders of placing the remaining mascots so that the number of steps where the occupied cells form a full rectangle is maximized, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
SpyGiven a subordinate subtree for every leader in two rooted trees of N employees, count for each IOI employee how many of the M spy projects succeed, where spy b succeeds when the matching JOI employee lies in research project b's subtree.	Hard8	TreeDFS+2	No attempts yet	2s	256 MB	Judgeable
White Day Present ExchangeEach student gives treats to one other student; choose whether each makes cookies or cake to maximize total happiness from what they receive.	Hard8	GraphDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
EquationCount integers n in [a, b] up to 10^18 with k times the sum of squares of n's decimal digits equal to n.	Hard8	MathBrute force+2	No attempts yet	2s	512 MB	Judgeable
ChampionshipsFind the largest set of vertices in an undirected graph that is connected and where every vertex has at least d neighbors inside the set.	Hard8	GraphImplementation+2	No attempts yet	2s	512 MB	Judgeable
JOI FlagFill and fix a 2^K by 2^K grid so it follows the recursive quadrant rule for JOI flags, minimizing the number of already-written cells whose character must change.	Hard8	Divide and conquerDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Inquiry IIGiven a connected simple graph with at most n+15 edges, output the size of its maximum independent set.	Hard8	TreeDFS+2	No attempts yet	5s	512 MB	Judgeable
Estate AgentGiven directed offers between families with amounts, pick a subset of disjoint cycles so the total sum of offer amounts is maximized, then output 5% of it.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Grand Central StationGiven a tree, find the minimum number of distinct map designs (rooted drawings) such that every vertex can be the center of one design after relabeling.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Hat StandPlace c-1 spare hats on hooks so the total walking distance over a given sequence of n hats is minimized, then output the best arrangement.	Hard8	GreedyDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Mosaic MansionGiven n rows of m colored tiles, remove rows so that the kept rows contain the same number of tiles of each color; maximize the number of kept rows.	Hard8	Dynamic programmingHash map+2	No attempts yet	12s	512 MB	Judgeable
DžumbusGiven a forest of N friends with drink thresholds, and Q queries each supplying a total drink S, find the maximum number of people who exchange solutions.	Hard8	Dynamic programmingTree+2	No attempts yet	1s	512 MB	Judgeable
Dice YutnoriGiven 10 die rolls, move one of four pieces around a branching Yutnori board each turn and maximize the score collected from numbered squares.	Hard8	BacktrackingSimulation+2	No attempts yet	2s	512 MB	Judgeable
Lion and RabbitCount the ordered pairs of distinct vertices in a connected undirected graph for which the lion can never catch the rabbit under simultaneous blind moves.	Hard8	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
Fibonacci MusicBuild a digit string from Fibonacci numbers reduced mod M and answer queries for the N-th digit, with N up to 10^15.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Copy and PasteGiven a string of up to 200,000 lowercase letters, find the length of the longest substring that appears at least twice at disjoint positions, or -1 if none exists.	Hard8	StringBinary search+2	No attempts yet	2s	512 MB	Judgeable
Cheese, If You PleaseGiven limited pounds of n cheese types and m blends with fixed percentage recipes and per-pound profits, find the maximum achievable profit and round it to the nearest cent.	Hard8	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Just Passing ThroughGrid path from the west edge to the east edge moving east, northeast, or southeast, crossing exactly n passes, minimizing total elevation.	Hard8	Dynamic programmingMatrix+2	No attempts yet	2s	512 MB	Judgeable
Where Have You Bin?Given a row of bins labeled by company, delete the listed bins, add the requested new bins, and find the minimum total item cost to keep every company's bins contiguous.	Hard8	Dynamic programmingImplementation+2	No attempts yet	1s	512 MB	Judgeable
Circle GardenGiven side lengths of a cyclic polygon, find the circumradius, or report no circle, an outside center, or a radius over 120 inches.	Hard8	GeometryMath+2	No attempts yet	1s	512 MB	Judgeable
Integers in Rational BasesGiven coprime p and q, write a positive integer n in the unique base p/q expansion whose digits are all at most p-1, printing digits 0-9, A-Z, a-z.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
HogwartsGiven two edge-labelled 4-out graphs on n rooms, decide whether every instruction sequence that walks from room 1 to room n in the old graph also walks from 1 to n in the new graph.	Hard8	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
MoleculesGiven a connected graph with some vertex positions fixed, find positions for the rest so each unknown vertex sits at the average of its neighbors; any valid solution is accepted.	Hard8	GraphMath+2	No attempts yet	2s	512 MB	Judgeable
Watch LaterGiven a string of video types, find the minimum number of manual clicks needed to watch everything, where playback auto-advances to the next video only if it has the same type.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	6s	512 MB	Judgeable
Pairing SocksGiven a sequence of 2n socks, find the minimum number of moves to pair all socks using two stacks with three allowed operations, or report impossible.	Hard8	StackGreedy+2	No attempts yet	1s	512 MB	Judgeable
Tree HuggingGiven 2(n-1) edges on n points, decide whether they can be split into a left-rooted increasing tree and a right-rooted decreasing tree, and output one such labeling.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Loo RollsFind the smallest number of loo rolls, each of length l, so that consuming n per visit never triggers a shortage.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Dice and LaddersFind the minimum number of die rolls so that the probability of finishing a snakes-and-ladders board within that many rolls is at least p.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Counting Permutations with a Given Greedily Increasing SubsequenceCount the permutations of 1 to N whose greedily increasing subsequence equals a given sequence G, modulo 1e9+7.	Hard8	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
Ranch CCTVFor each query, sheep in a grid shift one cell per day in a fixed direction for K days; report the XOR of the daily maximum over the CCTV rectangle.	Hard8	Prefix sumMatrix+2	No attempts yet	2s	256 MB	Judgeable
Pizza Grows as You Slice ItFor each K, choose the number of cuts that maximizes the pieces kept after giving away 1+2+...+k pieces to Yunhee.	Hard8	MathCombinatorics+1	No attempts yet	1s	256 MB	Judgeable
Warm Pork GukbapPlace any number of stores on a line of positions 1 to 50000, each store costs M, each delivery costs C times distance to nearest store; find the minimum total cost and the smallest number of stores achieving it.	Hard8	Dynamic programmingBinary search+2	No attempts yet	1s	256 MB	Judgeable
Max or MinGiven numbers on a circle and min/max operations over a value and its two neighbors, find for each x the least minutes to make all values equal x, or -1.	Hard8	ImplementationGreedy+2	No attempts yet	1s	256 MB	Judgeable
3D Points and QueriesCount points inside axis-aligned 3D boxes, where each query's box coordinates are decoded by XOR with the running sum of previous answers.	Hard8	Segment treeSorting+2	No attempts yet	7s	1024 MB	Judgeable
Game on a TreeAlice places a chip on a white node of a rooted tree, then players alternately move it to an unvisited ancestor or descendant, blackening that node; the player who cannot move loses. Determine the winner.	Hard8	TreeGame theory+2	No attempts yet	1s	256 MB	Judgeable
Strike ZoneGiven weighted point sets P1 (+c1 each) and P2 (-c2 each) with distinct x and y coordinates, find an axis-parallel rectangle maximizing c1s minus c2b.	Hard8	Dynamic programmingSorting+2	No attempts yet	1s	512 MB	Judgeable
WasherPartition up to 100 points in 3D into at most k groups (k <= 2) to minimize the sum of squared distances to each group's centroid.	Hard8	GeometryDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Drive SafelyPlace k speed limit signs on a polyline road so that travel time is minimized, where each turn caps the speed limit by \|180 - alpha\| km/h.	Hard8	Dynamic programmingGeometry+2	No attempts yet	1s	512 MB	Judgeable
EquilibriumGiven a tree, order its vertices to minimize the sum over vertices of the absolute difference between neighbors placed after and before them.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Great GDPGiven a vertex-weighted tree and a value and weight per node, find the connected subtree containing the root that maximizes total value divided by total weight.	Hard8	Binary searchGreedy+2	No attempts yet	1s	512 MB	Judgeable
Ice CreamGiven a capacitated pipe network with a chocolate source, a vanilla source, and a mixing sink, find the maximum flow that reaches the sink with equal chocolate and vanilla amounts.	Hard8	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Computer CacheMaintain a mutable byte array over m pieces, support range increments modulo 256 on a piece, cache loads of whole pieces into fixed cache positions, and point queries of cache bytes.	Hard8	Segment treeArray+2	No attempts yet	5s	512 MB	Judgeable
Fixed Point PermutationsFind the kth lexicographically smallest permutation of 1..n having exactly m fixed points, or print -1 if fewer than k exist.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Interstellar TravelGiven n angular intervals where each star contributes t - s*dist(a,b), find the launch angle b maximizing the sum of contributions.	Hard8	GeometryMath+2	No attempts yet	5s	512 MB	Judgeable
Jumping PathGiven a rooted tree with labels, find the length of the longest ancestor chain with nondecreasing labels, and count how many such chains of that length exist modulo 11092019.	Hard8	Dynamic programmingDFS+2	No attempts yet	10s	512 MB	Judgeable
Glow, Pixel, Glow!Given horizontal and vertical pulses crossing a grid of wires, count the pixels where current passes through both intersecting wires at the same time.	Hard8	SortingImplementation+2	No attempts yet	2s	512 MB	Judgeable
Cocoa CoalitionBreak an n by m chocolate bar with straight-line cuts into pieces that can be grouped into one pile of a cells and one of b cells, minimizing the number of cuts.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Building the Perfect HouseGiven N points, none at the origin, find the largest square centered at the origin that contains no point strictly inside it, then print its perimeter to four decimals.	Hard8	GeometryBinary search+2	No attempts yet	1.5s	512 MB	Judgeable
Cut Inequality DownFor many range queries [B,E] and starting wealth X, simulate monthly income with wealth clamped into [L,U] after each month and report the final wealth.	Hard8	Segment treeImplementation+2	No attempts yet	0.7s	512 MB	Judgeable
Dazzling StarsGiven N stars with coordinates and brightness, decide whether some rotation of the picture makes brighter stars print no later than dimmer ones, where printing goes top to bottom.	Hard8	GeometrySorting+2	No attempts yet	0.2s	512 MB	Judgeable
Hold or Continue?For each query state (Catelyn score, Hoster score, current turn total) decide hold or continue to maximize Catelyn's win probability when both play optimally in Pig to exactly 75.	Hard8	Dynamic programmingProbability+2	No attempts yet	2s	512 MB	Judgeable
Game of Falling BlocksSimulate a simplified Tetris game that uses bag randomization of the seven tetrominoes, and decide for each piece where to place it to complete at least one row before the game is lost.	Hard8	SimulationGreedy+2	No attempts yet	1s	512 MB	Judgeable
Gnoll HypothesisGiven n spawn probabilities and a random pool of k chosen types, compute each type's expected effective spawn chance after unchosen chances shift to the next chosen type cyclically.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
PopcountGiven N and K, produce a MalnarScript program of at most K commands that computes the popcount of an N-bit input using one variable.	Hard8	Bit manipulationDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
ICPCConcatenate all lowercase words of length 1 through N in length-then-alphabetical order; count occurrences of the substring "icpc" modulo 1e9+7, with N up to 1e9.	Hard8	CombinatoricsString matching+2	No attempts yet	2s	512 MB	Judgeable
Great Farmer Kim SanghyukChoose a radius r to maximize the daily profit from crops inside the circle (each worth wi times its distance to the boundary) minus the management cost A*r^2.	Hard8	GeometryMath+2	No attempts yet	2s	1024 MB	Judgeable
Optimal SelectionGiven n <= 8 numbers and some known pairwise order relations, find the worst-case minimum number of comparisons an optimal comparison-based algorithm needs to output the k-th smallest.	Hard8	Divide and conquerGame theory+2	No attempts yet	8s	1024 MB	Judgeable
Zeldain GardenSum the number of divisors of every integer from N to M, where N and M can reach 10^12.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Light Emitting HindenburgChoose K of N bitmask schedules to maximize the bitwise AND of their codes, reading the result as the group availability code.	Hard8	Bit manipulationGreedy+2	No attempts yet	1s	512 MB	Judgeable
K==SCount sequences of length N over 26 letters that avoid any of Q given forbidden strings as contiguous substrings, modulo 1e9+7, where N can be up to 1e9.	Hard8	String matchingDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
True/False WorksheetCount binary strings of length n that satisfy range hints, where each hint says a range is all equal or not all equal, modulo 1e9+7.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Ambiguous EncodingGiven a set of distinct binary codewords, decide whether two different character sequences can encode to the same bit string, and if so print the length of the shortest such string.	Hard8	String matchingBFS+2	No attempts yet	2s	512 MB	Judgeable
Sink the Billiard BallA point ball bounces off the edges of an A by B table with velocity (p,q); count edge hits until it reaches a corner, or print -1 if it never stops.	Hard8	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
Who Has Not Read the Message?Given each message's sender and the count of people who had not read it, count the possible sets of unread people per message, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Water Tanks of Seongdae CountryA tree of water tanks rooted at a capital. Adding water at city A adds 1,2,3,... along the root-to-A path. Answer queries about how much water a given city currently holds.	Hard8	TreeDFS+2	No attempts yet	1s	256 MB	Judgeable
Shortest Paths and QueriesGiven a grid with up to 5 rows and 100,000 columns, answer queries for the minimum-weight monotone-free path between two cells.	Hard8	Dynamic programmingMatrix+2	No attempts yet	5s	512 MB	Judgeable