Problems

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Total results29,416 problems

Rains Over Atlantis (Large)
Hard8
Heap, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Ace in the Hole (Small)
Hard8
Game theory, Brute force+1
No attempts yet
Time limit
30s
Memory limit
512 MB
Judgeable
Google Royale
Hard8
Dynamic programming, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Mystery Square (Large)
Hard8
Number theory, Backtracking+1
No attempts yet
Time limit
60s
Memory limit
512 MB
Judgeable
Perfect Harmony (Large)
Hard8
Number theory
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Champion Sort (Small)
Hard8
Probability, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Extreme Escalator Pogo (Large)
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
City Tour
Hard8
Dynamic programming, Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Travel Plan (Large)
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Ninjutsu (Small)
Hard8
Geometry, Backtracking
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fence Boards
Hard8
Shortest path, Dynamic programming+1
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
Sums with Distinct Column Digits
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Counting Cryptarithm Equations
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
60s
Memory limit
512 MB
Judgeable
Bacteria
Hard8
Dynamic programming, Matrix
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Grazing Goats
Hard8
Geometry
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Polygraph (Large)
Hard8
Union-find, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Minimum Triangle Perimeter
Hard8
Geometry, Divide and conquer+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Minimum Triangle Perimeter
Hard8
Geometry, Divide and conquer+1
No attempts yet
Time limit
90s
Memory limit
512 MB
Judgeable
Marbles
Hard8
Dynamic programming, Implementation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Two Lights in a Square Room
Hard8
Geometry, Implementation+2
No attempts yet
Time limit
40s
Memory limit
512 MB
Judgeable
EZ-Sokoban (Small)
Hard8
BFS, Simulation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Interesting Ranges
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
45s
Memory limit
512 MB
Judgeable
Stock Charts
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Watering Plants
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bridge Builders (Small)
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bridge Builders (Large)
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Year of Code Jam (Small)
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Year of Code Jam (Large)
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Painting a Fence (Large)
Hard8
Intervals, Greedy+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Bus Stops (Small)
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bus Stops (Large)
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Code Sequence (Large)
Hard8
Math, Bit manipulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Test Passing Probability (Large Input)
Hard8
Probability, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Apocalypse Soon (Large)
Hard8
Simulation, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Becoming a Millionaire
Hard8
Dynamic programming, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Millionaire (Large)
Hard8
Dynamic programming, Probability
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
How Big Are the Pockets? (Large)
Hard8
Geometry, Simulation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Portal Gun and Cake
Hard8
BFS, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Portal
Hard8
BFS, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Poklon
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Minimum transmitter power
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
PermRLE (Large)
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Increasing Speed Limits (Large)
Hard8
Dynamic programming, Segment tree
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fly Swatter (Small)
Hard8
Geometry, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fly Swatter (Large)
Hard8
Geometry, Math+2
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
Boat
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fireworks
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bosses
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Spiral Rectangle Sums
Hard8
Math, Implementation+2
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Balanced Diet
Hard8
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Rivers
Hard8
Tree, Prefix sum+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
The Great Mixing Song Festival
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Half-plane land grab
Hard8
Geometry, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Relay Signal
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bridge testing
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Similar Subways
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Hyperways
Hard8
Union-find, Graph+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Dynamic memory allocation
Hard8
Intervals, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Shades of the town
Hard8
String matching, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Investigation
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Wall Repair
Hard8
Dynamic programming, Intervals+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Next 3-1-2 pattern avoiding permutation
Hard8
Combinatorics, Greedy+1
No attempts yet
Time limit
0.1s
Memory limit
32 MB
Judgeable
Newspapers
Hard8
Binary search, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Organizing Cards 2
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Walk on the Main Campus 2
Hard8
Graph, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hongjun Likes Physics
Hard8
Graph, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun Loves Painting
Hard8
Segment tree, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun Likes Strings
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Range GCD
Hard8
Segment tree, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Remainder Game
Hard8
Dynamic programming, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Love Triangles
Hard8
Graph, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
First Pair to Meet
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Journey
Hard8
Shortest path, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Lot of Games
Hard8
Trie, Game theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Finding an integer
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maximum substring cost
Hard8
String, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Block Puzzle
Hard8
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Heroes Never Die
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Favorite Arrays 2
Hard8
Dynamic programming, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Substring Count
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Energy Management
Hard8
Greedy, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Coin Game
Hard8
Game theory, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Flipping a Bit String
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number of Simple Cycles
Hard8
Backtracking, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Direction Board
Hard8
Graph, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chessboard
Hard8
Dynamic programming, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chessboard 2
Hard8
Graph, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Running Race
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of Scores
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Red segments and blue segments
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Array GCD
Hard8
Number theory, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Points on a Circle
Hard8
Probability, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Favorite Sequence
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting strings with LCS n-1
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun's Intersection
Hard8
Sorting, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Run and Swim Race
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Decorating with Flowers
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun and the Possible Sets
Hard8
Tree, DFS+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Kiwi Juice
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Special Ability
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Rains Over Atlantis (Large)Given a height grid and a daily erosion cap, compute how many days of water-level erosion flatten the whole map to zero.	Hard8	HeapGraph+1	No attempts yet	5s	512 MB	Judgeable
Ace in the Hole (Small)Reconstruct the lexicographically greatest 321-avoiding permutation consistent with the given optimal worst-case search order for value 1.	Hard8	Game theoryBrute force+1	No attempts yet	30s	512 MB	Judgeable
Google RoyalePick starting and doubling coin-flip bets to maximize the chance of growing A dollars into V dollars before going broke.	Hard8	Dynamic programmingProbability+1	No attempts yet	5s	512 MB	Judgeable
Mystery Square (Large)Fill each ? in the binary string with 0 or 1 so the result is the binary form of a perfect square.	Hard8	Number theoryBacktracking+1	No attempts yet	60s	512 MB	Judgeable
Perfect Harmony (Large)Find the smallest frequency from L to H that divides or is a multiple of every given frequency, else print NO.	Hard8	Number theory	No attempts yet	10s	512 MB	Judgeable
Champion Sort (Small)Compute the minimum expected number of random subset shuffles that sorts a permutation of 1 to N into increasing order.	Hard8	ProbabilityCombinatorics+1	No attempts yet	5s	512 MB	Judgeable
Extreme Escalator Pogo (Large)Pick a starting blue step and a sequence of jump heights that change by at most one each time to maximize the tallest jump before a red landing.	Hard8	GraphDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
City TourFind the longest simple cycle in a graph grown from a triangle by joining each new vertex to both ends of an existing edge.	Hard8	Dynamic programmingGraph	No attempts yet	5s	512 MB	Judgeable
Travel Plan (Large)Visit every planet on a line exactly once and return to Earth, maximizing total travel distance without exceeding the fuel limit.	Hard8	Dynamic programmingSorting+1	No attempts yet	5s	512 MB	Judgeable
Ninjutsu (Small)Cut the rope to any length up to R so the counterclockwise swing bends around the maximum number of point targets.	Hard8	GeometryBacktracking	No attempts yet	5s	512 MB	Judgeable
Fence BoardsPick the fewest boards from N unlimited lengths to total exactly L for a fence up to 1e18 long, or report IMPOSSIBLE.	Hard8	Shortest pathDynamic programming+1	No attempts yet	20s	512 MB	Judgeable
Sums with Distinct Column DigitsCount unordered additions that sum to N in base B where digits in each column are pairwise distinct, modulo 1000000007.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	5s	512 MB	Judgeable
Counting Cryptarithm EquationsCount unordered base-B summand sets with distinct digits in each column that sum to N.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	60s	512 MB	Judgeable
BacteriaRectangular colonies on a grid evolve each second by a north-and-west neighbor rule, and the task asks when every cell becomes empty.	Hard8	Dynamic programmingMatrix	No attempts yet	5s	512 MB	Judgeable
Grazing GoatsFor each candidate bucket point, fix each rope at its pole distance and compute the area shared by all disks.	Hard8	Geometry	No attempts yet	5s	512 MB	Judgeable
Polygraph (Large)Each of N people is a truth-teller or a liar; given their statements about who shares which city, mark each person as forced Truthtown, forced Liarville, or undetermined.	Hard8	Union-findGraph+1	No attempts yet	5s	512 MB	Judgeable
Minimum Triangle PerimeterGiven up to 10000 points, find three whose triangle has the smallest total perimeter, with collinear triples allowed.	Hard8	GeometryDivide and conquer+1	No attempts yet	5s	512 MB	Judgeable
Minimum Triangle PerimeterGiven up to a million integer points, pick three that form the triangle of smallest perimeter and report that perimeter.	Hard8	GeometryDivide and conquer+1	No attempts yet	90s	512 MB	Judgeable
MarblesGiven 2n marbles of n colors in a row, find the minimum height of non-crossing paths pairing each color, or -1 if impossible.	Hard8	Dynamic programmingImplementation+1	No attempts yet	5s	512 MB	Judgeable
Two Lights in a Square RoomGiven two point lights and up to 50 circular pillars inside a square, find the area lit by neither, by red only, by green only, and by both.	Hard8	GeometryImplementation+2	No attempts yet	40s	512 MB	Judgeable
EZ-Sokoban (Small)Move at most three magnetized boxes on a grid to their goal cells with the fewest pushes, where boxes must stay connected except for at most one push.	Hard8	BFSSimulation+2	No attempts yet	5s	512 MB	Judgeable
Interesting RangesCount subranges of [L, R] containing an even number of decimal palindromes, for L and R up to 10^100, modulo 1e9+7.	Hard8	MathCombinatorics+1	No attempts yet	45s	512 MB	Judgeable
Stock ChartsPartition n stock price sequences into the fewest groups so that within each group no two polylines cross or touch at any time point.	Hard8	Dynamic programmingGreedy+1	No attempts yet	5s	512 MB	Judgeable
Watering PlantsGiven N disjoint disks, find the smallest radius R such that two disks of radius R can cover all the plants.	Hard8	GeometryBinary search+2	No attempts yet	5s	512 MB	Judgeable
Bridge Builders (Small)Connect all island cells on a grid with bridges, minimizing total cost, where each bridge's cost grows with the distance from the nearest forest already linked to the base camp.	Hard8	GraphMinimum spanning tree+2	No attempts yet	5s	512 MB	Judgeable
Bridge Builders (Large)Connect all island cells with bridges from a forest, where each bridge costs the walking distance from the nearest forest, and minimize total man-hours.	Hard8	GraphMinimum spanning tree+2	No attempts yet	5s	512 MB	Judgeable
The Year of Code Jam (Small)Assign each '?' day blue or white to maximize total blue-day value, where a blue day starts at 4 and loses 1 for each blue neighbor above, below, left, or right in a grid of N months by M days.	Hard8	Dynamic programmingGraph+2	No attempts yet	5s	512 MB	Judgeable
The Year of Code Jam (Large)On a grid of N months by M days, choose white or blue for each '?' cell to maximize total happiness, where each blue day scores 4 minus its blue neighbors.	Hard8	Dynamic programmingGraph+2	No attempts yet	5s	512 MB	Judgeable
Painting a Fence (Large)Pick the fewest offers from N interval-and-color proposals so every one of 10000 fence sections is covered using at most 3 distinct colors.	Hard8	IntervalsGreedy+2	No attempts yet	10s	512 MB	Judgeable
Bus Stops (Small)Count the ways K buses starting at the first K stops can cover all N stops and end at the last K, with gaps of at most P.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	5s	512 MB	Judgeable
Bus Stops (Large)Count schedules assigning every stop to one of K left-to-right buses whose consecutive stops are at most P apart, modulo 30031.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	5s	512 MB	Judgeable
Code Sequence (Large)Given consecutive terms of a binary-additive sequence with unknown coefficients, output the next term or UNKNOWN if it is not forced.	Hard8	MathBit manipulation+1	No attempts yet	5s	512 MB	Judgeable
Test Passing Probability (Large Input)With M submissions allowed and independent per-question probabilities, choose answers to maximize the chance that one submission is fully correct.	Hard8	ProbabilityDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
Apocalypse Soon (Large)On a grid of nations attacking their strongest living neighbor each day, choose your own attacks to maximize how many days your nation survives.	Hard8	SimulationGreedy+2	No attempts yet	5s	512 MB	Judgeable
Becoming a MillionaireBet any fraction of your money each round to maximize the chance of ending with at least one million dollars.	Hard8	Dynamic programmingProbability+1	No attempts yet	5s	512 MB	Judgeable
Millionaire (Large)Bet any fraction of your money over M rounds with win probability P; maximize the chance of holding $1,000,000 at the end.	Hard8	Dynamic programmingProbability	No attempts yet	20s	512 MB	Judgeable
How Big Are the Pockets? (Large)A run-length-encoded turtle walk traces a simple closed lattice polygon; compute the total area of all points outside it that have boundary both east and west or both north and south.	Hard8	GeometrySimulation+2	No attempts yet	5s	512 MB	Judgeable
Portal Gun and CakeFind the minimum number of moves to reach the cake in a small grid where portals can be placed on walls and traversed.	Hard8	BFSGraph+1	No attempts yet	5s	512 MB	Judgeable
PortalFind the fewest moves to reach the cake in a walled grid, where firing a portal gun at walls (free of move cost) lets you teleport between two portal openings.	Hard8	BFSGraph+2	No attempts yet	5s	512 MB	Judgeable
PoklonGiven a tree of scales, add positive real weights so every scale balances with minimum total added mass, then print the final total mass in binary.	Hard8	TreeDFS+2	No attempts yet	1s	256 MB	Judgeable
Minimum transmitter powerPlace a flagship in 3D so the maximum weighted Manhattan distance to N ships is minimized, and report that minimum power rounded to six decimals.	Hard8	GeometryBinary search+2	No attempts yet	5s	512 MB	Judgeable
PermRLE (Large)Find the permutation of positions 1 to k applied to every block of the string that minimizes the number of runs after run-length encoding.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	5s	512 MB	Judgeable
Increasing Speed Limits (Large)Generate a sequence from a recurrence, then count modulo 1e9+7 how many non-empty strictly increasing subsequences it has.	Hard8	Dynamic programmingSegment tree	No attempts yet	5s	512 MB	Judgeable
Fly Swatter (Small)Compute the probability that a randomly placed fly disk touches a circular ring crossed by a grid of cylindrical strings, and print it to six decimals.	Hard8	GeometryMath+2	No attempts yet	5s	512 MB	Judgeable
Fly Swatter (Large)Given the racquet geometry, compute the probability that a fly of radius f, centered uniformly in the outer circle, overlaps the ring or any string.	Hard8	GeometryMath+2	No attempts yet	20s	512 MB	Judgeable
BoatCount subsets of schools with an assigned boat count in [a_i, b_i], strictly increasing in school order, excluding the empty setup, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
FireworksGiven a rooted tree whose leaves are explosives and whose edges have lengths, find the minimum total change of edge lengths so all leaves ignite at the same time.	Hard8	TreeDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
BossesBuild a rooted tree on n employees where each node's parent is one of its accepted bosses, then assign minimum positive salaries with every boss exceeding the sum of children.	Hard8	TreeDynamic programming+2	No attempts yet	1.5s	256 MB	Judgeable
Spiral Rectangle SumsIn a counterclockwise spiral of numbers on a (2n+1)x(2n+1) grid centered at 1, answer q queries for the sum inside an axis-aligned rectangle modulo 1e9+7.	Hard8	MathImplementation+2	No attempts yet	1.5s	256 MB	Judgeable
Balanced DietGiven proportional target fractions and a balanced eating history, find how many more candies can be added with every prefix staying balanced, or report forever.	Hard8	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Longest RiversGiven a river network tree and source names, find for each name the best rank it can achieve over all valid downstream naming choices.	Hard8	TreePrefix sum+2	No attempts yet	10s	512 MB	Judgeable
The Great Mixing Song FestivalPartition the given songs into groups of exactly c songs each within a year span of m, maximizing the total length of the longest common substring in each group.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	5s	128 MB	Judgeable
Half-plane land grabLines are added one at a time, and after each addition you must report the maximum y value over all added lines at a given x.	Hard8	GeometryDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Relay SignalCount boats reachable within one relay hop from boat 1, where visibility means the connecting segment never enters the convex island interior; every coordinate is a lattice point.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Bridge testingGiven a weighted tree and two timed walkers on their respective paths, decide for each query whether both occupy some bridge simultaneously over a positive-length interval.	Hard8	TreeDynamic programming+2	No attempts yet	4s	256 MB	Judgeable
Similar SubwaysGiven two trees with up to 50 nodes each, find the largest k such that some connected k-node subtree of the first is isomorphic to some connected k-node subtree of the second.	Hard8	TreeDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
HyperwaysAfter each edge is added to a multigraph, report how many edges became safe, where an edge is safe when it lies on a cycle.	Hard8	Union-findGraph+2	No attempts yet	3s	1024 MB	Judgeable
Dynamic memory allocationSimulate a memory allocator over n bytes: allocate the leftmost run of l free bytes, or free a range and count how many bytes were actually freed.	Hard8	IntervalsSegment tree+1	No attempts yet	1s	1024 MB	Judgeable
Shades of the townGiven several integer patterns and one shade array, count every occurrence where a contiguous block equals a pattern scaled by a positive real factor.	Hard8	String matchingMath	No attempts yet	1s	1024 MB	Judgeable
InvestigationGiven a tree and a thief hidden at one node, find the minimum worst-case number of queries to locate him in an optimal search strategy.	Hard8	TreeDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Wall RepairA robot on a line must visit every point; each point's repair cost grows linearly with the time it waits, so find the visiting order of minimum total cost.	Hard8	Dynamic programmingIntervals+2	No attempts yet	1s	1024 MB	Judgeable
Next 3-1-2 pattern avoiding permutationGiven a 3-1-2-avoiding permutation of 1 to n, print the next one in lexicographic order.	Hard8	CombinatoricsGreedy+1	No attempts yet	0.1s	32 MB	Judgeable
NewspapersGiven a weighted tree, find the maximum average edge weight over all simple paths that contain at least k edges, printed to eight decimals.	Hard8	Binary searchDynamic programming+2	No attempts yet	4s	1024 MB	Judgeable
Organizing Cards 2Given N boxes and M colors with per-box color counts, move individual cards so each color occupies exactly one box, minimizing total moves.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Walk on the Main Campus 2Count closed walks of exactly D minutes from building 1 back to building 1 in a given 8-vertex graph, modulo 1e9+7.	Hard8	GraphMatrix+2	No attempts yet	1s	512 MB	Judgeable
Hongjun Likes PhysicsFind the connected induced subgraph maximizing (sum of vertex weights)/(sum of edge weights) and print its density. A fractional programming problem solved by binary searching the ratio with a maximum closure computation.	Hard8	GraphBinary search+1	No attempts yet	2s	512 MB	Judgeable
Hongjun Loves PaintingBricks start with color equal to their index and colorfulness 0; range paint operations add the absolute color change to each brick, and queries ask for the total colorfulness over a range.	Hard8	Segment treeImplementation+2	No attempts yet	2s	512 MB	Judgeable
Hongjun Likes StringsFor each of up to 100000 queries, find the shortest substring of a fixed string S that contains both given short patterns A and B, allowing overlap.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Range GCDSupport range add and range GCD queries on an array by tracking a difference array with a segment tree and one prefix sum.	Hard8	Segment treeNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Remainder GameCount ways to pick one block per basket, forming a b-digit number whose remainder mod x is k, where baskets share the same multiset of digits.	Hard8	Dynamic programmingMatrix+2	No attempts yet	2s	512 MB	Judgeable
Love TrianglesCount the ways to label every remaining pair in a graph as like or dislike so that no triple has exactly two liking pairs, given some fixed edges.	Hard8	GraphCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
First Pair to MeetGiven people at vertices of a weighted undirected graph, find the minimum over all pairs of half their shortest-path distance; roads are traversed at 10 km/h and the time prints in minutes.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
JourneyTwo weighted graphs share vertices; alternate one edge per graph, each strictly decreasing that graph's distance to t, and find the longest total route or -1 if infinite.	Hard8	Shortest pathDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
A Lot of GamesGiven a trie of strings, play the prefix-building game k times with the loser starting next; report who wins the last game.	Hard8	TrieGame theory+2	No attempts yet	2s	512 MB	Judgeable
Finding an integerFind the smallest integer at least N whose decimal digits contain d1 at least c1 times and d2 at least c2 times.	Hard8	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable
Maximum substring costGiven a string T, find the maximum of length times number of occurrences over all substrings S of T.	Hard8	StringSorting+2	No attempts yet	2s	512 MB	Judgeable
Block PuzzleOn an N by N grid, roll a 1x1x2 block from any start cell to the goal without falling into holes; find the fewest cells to dig into holes so the goal becomes unreachable.	Hard8	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Heroes Never DieChoose a subset of heroes to revive, gaining bond rewards when both endpoints are chosen, to maximize total reward minus revival cost.	Hard8	GraphMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Favorite Arrays 2Count length-N arrays with entries in 1..K where no adjacent pair has A > B with A divisible by B, modulo 1e9+7.	Hard8	Dynamic programmingNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Substring CountCount length-L lowercase strings that contain exactly C of N given words (N at most 6, L at most 50) as substrings, modulo 1,000,000,009.	Hard8	Dynamic programmingString matching+2	No attempts yet	2s	512 MB	Judgeable
Energy ManagementWith E energy, recovery R per day capped at E, and per-day weights c_i, maximize the weighted sum of energy spent over N days.	Hard8	GreedyMath	No attempts yet	2s	512 MB	Judgeable
Coin GameGiven n coin piles and a fixed k, players alternately remove a coin or split an even pile into k equal halves; decide the winner under optimal play.	Hard8	Game theoryMath+1	No attempts yet	2s	512 MB	Judgeable
Flipping a Bit StringGiven a binary string and a divisor M of its length, find the minimum number of operations (single flip, prefix flip of a multiple of M, or suffix flip of a multiple of M) to make all characters 1.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Number of Simple CyclesGiven two trees on N vertices with N up to 9, choose a bijection linking them to maximize the number of simple cycles of length K.	Hard8	BacktrackingGraph+2	No attempts yet	2s	512 MB	Judgeable
Direction BoardGiven a toroidal N x M grid of arrows (N,M <= 15), change the fewest arrows so that every cell lies on a cycle of length 1.	Hard8	GraphBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
ChessboardPlace as many L-trominoes as possible on a board at most 4 rows tall, where each tile's corner cell must sit on a black square and pieces block cells.	Hard8	Dynamic programmingBit manipulation	No attempts yet	2s	512 MB	Judgeable
Chessboard 2Place as many non-overlapping L-trominoes as possible on a grid with blocked cells, with each tile's corner on a black square.	Hard8	GraphBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Running RaceFind the maximum flow from node 0 to node N-1 in an undirected graph where road i has capacity 3^i, and print it modulo 1e9+7.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Sum of ScoresFind a non-empty vertex subset connected in both given trees whose score sum is maximized, with vertex counts up to 50.	Hard8	Dynamic programmingTree+1	No attempts yet	2s	512 MB	Judgeable
Red segments and blue segmentsColor N points red or blue, then draw non-crossing same-color segments so that no red and blue segment touch; maximize total segment scores.	Hard8	Dynamic programmingGeometry+2	No attempts yet	2s	512 MB	Judgeable
Array GCDDelete one contiguous block and change at most one element by 1 each, so the remaining array has gcd greater than 1, at minimum cost.	Hard8	Number theoryGreedy+2	No attempts yet	2s	512 MB	Judgeable
Points on a CircleGiven n random points on a unit circle and an angle p, compute -log2 of the probability that all n points fit inside some arc of central angle p.	Hard8	ProbabilityMath+2	No attempts yet	2s	512 MB	Judgeable
Favorite SequenceCount fillings of at most 5 erased positions in a permutation so the number of pairs i<j with A_i<A_j equals S.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Counting strings with LCS n-1Count length-n strings over the first m letters whose longest common subsequence with a given string S has length exactly n-1.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Hongjun's IntersectionSum the lengths of the intersections of all k-subsets of given segments, modulo 1e9+7.	Hard8	SortingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Run and Swim RaceGiven each runner's running and swimming speeds, find every participant who can finish first for some positive choice of the leg lengths R and S.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Decorating with FlowersCount the ways to choose exactly s blossoms from n kinds with limits f_i, modulo 1e9+7, where n is at most 18 and s can reach 1e14.	Hard8	CombinatoricsMath+1	No attempts yet	2s	512 MB	Judgeable
Hongjun and the Possible SetsCount the nonempty connected vertex subsets of a weighted tree whose maximum minus minimum weight is at most d.	Hard8	TreeDFS+2	No attempts yet	3s	512 MB	Judgeable
Kiwi JuicePour juice between N bottles of capacity C, each pour filling or emptying one, to maximize the sum of prices over all final amounts.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Special AbilityFind the minimum cost walk from vertex 1 to N in a directed weighted graph, where the ability can negate the weight of at most C edge crossings.	Hard8	GraphShortest path+1	No attempts yet	2s	512 MB	Judgeable