Problems

Pick a problem, code in the editor, and watch the judge run real test cases. The archive is open to browse

Under construction

Still being built. Things may change

Total results29,041 problems

Fenced In (Gold)
Medium7
Minimum spanning tree, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Reassembling the Glass Cow
Medium7
Brute force, Geometry+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Landscaping
Medium7
Dynamic programming, Graph
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Treasure Hunt
Medium7
Math, Binary search
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Yonsei University Point Game
Medium7
Divide and conquer, Tree+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Sums of Sums (Large)
Medium7
Binary search, Two pointers+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Virtual Rabbit (Large)
Medium7
Greedy, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Elf Tournament Lineup
Medium7
Backtracking, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Travel (Small)
Medium7
Shortest path, Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Travel (Large)
Medium7
Shortest path, Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
gWheels (Large)
Medium7
Number theory, Hash map
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
gNumbers
Medium7
Game theory, Number theory+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
gNumber Game (Large)
Medium7
Game theory, Number theory+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Albocede DNA (Small)
Medium7
Dynamic programming, String+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Snake Game Simulation
Medium7
Simulation, Queue+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Divisor erasing game 1
Medium7
Game theory, Number theory
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Divisor Erasing Game 2
Medium7
Game theory, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Costly Binary Search (Small)
Medium7
Dynamic programming, Tree+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Campground Arrangements (Small)
Medium7
Combinatorics, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Pretty Good Proportion (Large)
Medium7
Prefix sum, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Taking Over The World (Small)
Medium7
Shortest path, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Merlin QA
Medium7
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Crane Truck (Large)
Medium7
Simulation, Math
No attempts yet
Time limit
120s
Memory limit
512 MB
Judgeable
Smoothing Window (Large)
Medium7
Binary search, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Runaway Quail
Medium7
Dynamic programming, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Log Set (Small)
Medium7
Backtracking, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
River Flow (Large)
Medium7
Bit manipulation, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Kiddie Pool
Medium7
Binary search, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Kiddie Pool
Medium7
Binary search, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
English and French (Large)
Medium7
Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Brattleship
Medium7
Game theory, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Less Money, More Problems
Medium7
Greedy, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Counter Culture (Large)
Medium7
Greedy, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Noisy Neighbors (Large)
Medium7
Combinatorics, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hiking Deer (Small1)
Medium7
Greedy, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Logging
Medium7
Geometry, Brute force
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Logging (Large)
Medium7
Geometry
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
Dijkstra (Large)
Medium7
Math, Simulation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Card Game
Medium7
Dynamic programming, Intervals
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Card Game (Large)
Medium7
Dynamic programming, Intervals
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Symmetric Trees (Large)
Medium7
Tree, Recursion+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Paradox Sort (Large)
Medium7
Graph, DFS+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Allergy Testing (Small)
Medium7
Dynamic programming
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Allergy Testing (Large)
Medium7
Dynamic programming, Binary search+1
No attempts yet
Time limit
90s
Memory limit
512 MB
Judgeable
ARAM (Small)
Medium7
Dynamic programming, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Don't Break the Nile (Small)
Medium7
Graph, Matrix
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Reordering Train Cars (Small)
Medium7
Graph, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Reordering Train Cars (Large)
Medium7
Graph, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Enclosing Grid Points
Medium7
Geometry, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
New Lottery Game (Large)
Medium7
Dynamic programming, Bit manipulation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Full Binary Tree (Large)
Medium7
Dynamic programming, Tree+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Minesweeper Master
Medium7
Implementation, Simulation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Minesweeper Master
Medium7
Implementation, Matrix
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Spaceship Defence (Large)
Medium7
Shortest path, Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hamiltonian Circuit
Medium7
Graph, Simulation
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Graduation Requirements (Large)
Medium7
Intervals, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Drummer (Small)
Medium7
Math, Brute force
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Drummer (Large)
Medium7
Binary search, Geometry+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
X Marks the Spot (Small)
Medium7
Geometry, Brute force
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Can't Stop (Large)
Medium7
Sliding window, Backtracking
No attempts yet
Time limit
30s
Memory limit
512 MB
Judgeable
Let Me Tell You a Story (Small)
Medium7
Dynamic programming, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Rigged Roulette
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Are We Lost Yet? (Small)
Medium7
Shortest path, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Are We Lost Yet? (Large)
Medium7
Shortest path, Greedy
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Observation Wheel
Medium7
Dynamic programming, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Ticket Swapping (Small)
Medium7
Greedy, Stack+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Many Prizes (Small)
Medium7
Combinatorics, Greedy
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Erdős and Szekeres Sequence Reconstruction
Medium7
Backtracking, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Erdős-Szekeres (Large)
Medium7
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Pogo Stick
Medium7
Math, Greedy
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Pogo (Large)
Medium7
Math, Greedy
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Garbled Email
Medium7
Dynamic programming, Trie+1
No attempts yet
Time limit
60s
Memory limit
512 MB
Judgeable
The Number Trick
Medium7
Brute force, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
1536 MB
Judgeable
Opening the Treasure Chests
Medium7
Greedy, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Professor Normal (Small2)
Medium7
Simulation, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Perfect Game
Medium7
Greedy, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Perfect Game
Medium7
Greedy, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Havannah Winning Structures
Medium7
Union-find, BFS
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Quality Food (Large)
Medium7
Binary search, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Swinging Wild
Medium7
Graph, BFS+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Descending in the Dark (Small)
Medium7
BFS, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Out of gas
Medium7
Greedy, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Out of Gas (Large)
Medium7
Greedy, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Box Factory (Large)
Medium7
Dynamic programming, String matching
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Tide Goes In, Tide Goes Out (Small)
Medium7
Shortest path, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cruise Control (Small)
Medium7
Brute force, Simulation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cruise Control (Large)
Medium7
Graph, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Street Tree Props (Large)
Medium7
Greedy, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Sunlight (Large)
Medium7
Geometry, Intervals+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Breaking Windows (Small)
Medium7
Probability, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Breaking Windows (Large)
Medium7
Probability, Combinatorics+1
No attempts yet
Time limit
30s
Memory limit
512 MB
Judgeable
Battlefield (Large)
Medium7
Brute force, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Yut Nori Board Check (Small)
Medium7
Backtracking, Simulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bacteria (Small)
Medium7
Graph, BFS+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bacteria (Large)
Medium7
Graph, BFS+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Survivor (Large)
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Market Board (Large)
Medium7
Probability, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Children Wearing Hats (Small)
Medium7
Game theory, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Restoring the Erased Equation (Large)
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bacteria Growth (Small)
Medium7
Number theory, Recursion
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Fenced In (Gold)Remove fence segments of minimum total length so every region of the fenced grid connects to every other.	Medium7	Minimum spanning treeGreedy+1	No attempts yet	2s	512 MB	Judgeable
Reassembling the Glass CowCount the triples of scattered pieces that rebuild the colored figurine after rotation, reflection, and shifting.	Medium7	Brute forceGeometry+2	No attempts yet	5s	512 MB	Judgeable
LandscapingMove, buy, or remove dirt so each of N flowerbeds reaches its target amount at minimum total cost.	Medium7	Dynamic programmingGraph	No attempts yet	2s	512 MB	Judgeable
Treasure HuntGiven a and b, find the shared limit of the arithmetic and harmonic mean iteration, which is sqrt(a b), printed to three decimals.	Medium7	MathBinary search	No attempts yet	1s	128 MB	Judgeable
Yonsei University Point GamePlayers paint tree nodes blue and queries ask for the sum of weighted distances from a node to all painted nodes.	Medium7	Divide and conquerTree+1	No attempts yet	5s	128 MB	Judgeable
Sums of Sums (Large)Given a positive array, sort all its subarray sums and answer the sum of entries ranked L through R for each query.	Medium7	Binary searchTwo pointers+1	No attempts yet	5s	512 MB	Judgeable
Virtual Rabbit (Large)Find the fewest feedings over D days so no gap exceeds X seconds while skipping work and sleep hours.	Medium7	GreedyMath+1	No attempts yet	5s	512 MB	Judgeable
Elf Tournament LineupDecide whether 2^N elves can be lined up for a knockout tournament so every sensitive elf avoids its listed friends through the first K rounds.	Medium7	BacktrackingGraph+1	No attempts yet	5s	512 MB	Judgeable
Travel (Small)Starting from city 1 at given hours, find the fastest route to each destination on roads whose travel time depends on the departure hour.	Medium7	Shortest pathGraph	No attempts yet	5s	512 MB	Judgeable
Travel (Large)Given roads whose travel time depends on the departure hour, find the fastest trip from city 1 for each query destination and start hour.	Medium7	Shortest pathGraph	No attempts yet	5s	512 MB	Judgeable
gWheels (Large)Decide whether pedal, middle, and tire gear choices with two different middle gears produce each target speed ratio.	Medium7	Number theoryHash map	No attempts yet	15s	512 MB	Judgeable
gNumbersTwo players alternately remove every copy of one prime factor from the current number, and whoever faces a number whose digit sum is 1 or prime loses.	Medium7	Game theoryNumber theory+1	No attempts yet	5s	512 MB	Judgeable
gNumber Game (Large)Players alternate removing one prime factor entirely from N, and whoever faces a number with digit sum 1 or prime loses; report the winner under optimal play.	Medium7	Game theoryNumber theory+1	No attempts yet	5s	512 MB	Judgeable
Albocede DNA (Small)Count subsequences of S that split into blocks of the form a^i b^j c^i d^j with i and j at least 1, modulo 1e9+7.	Medium7	Dynamic programmingString+1	No attempts yet	5s	512 MB	Judgeable
Snake Game SimulationSimulate a snake that grows on checkerboard food on a wrapping board with timed turns and report its length after death or one billion steps.	Medium7	SimulationQueue+2	No attempts yet	5s	512 MB	Judgeable
Divisor erasing game 1Players alternate erasing a remaining number from 1 to N with its divisors, the player taking the last number loses, so name the winner under optimal play.	Medium7	Game theoryNumber theory	No attempts yet	2s	512 MB	Judgeable
Divisor Erasing Game 2Given the board numbers, print for each possible first pick every reply that lets the second player force a win.	Medium7	Game theoryDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Costly Binary Search (Small)Find the comparison order that minimizes the worst-case total cost of locating the insertion position when each array slot has its own comparison cost.	Medium7	Dynamic programmingTree+1	No attempts yet	5s	512 MB	Judgeable
Campground Arrangements (Small)Count N by N grids with entries 0 to 3 where each row and column sums to 3 with at most two tents and at least X cells hold 3.	Medium7	CombinatoricsMath+1	No attempts yet	5s	512 MB	Judgeable
Pretty Good Proportion (Large)Given a binary string and a target fraction F, find the smallest starting position among substrings whose proportion of 1s is closest to F.	Medium7	Prefix sumSorting	No attempts yet	5s	512 MB	Judgeable
Taking Over The World (Small)Block up to K rooms to make the fastest route from the entrance to the weapon room, counting one extra step per blocked room, as long as possible.	Medium7	Shortest pathGraph+1	No attempts yet	5s	512 MB	Judgeable
Merlin QAPick the order to cast every spell once so the ingredients left at the end have the largest possible total value.	Medium7	GreedySorting	No attempts yet	5s	512 MB	Judgeable
Crane Truck (Large)Simulate a crane truck program with up to two flat loops on 240 circular cells with modulo-256 counters and count its moves before it halts.	Medium7	SimulationMath	No attempts yet	120s	512 MB	Judgeable
Smoothing Window (Large)Given N, K and every window sum of a hidden integer sequence, find the smallest max-minus-min range among all integer sequences that match.	Medium7	Binary searchMath+1	No attempts yet	5s	512 MB	Judgeable
Runaway QuailCatch quails that flee in both directions on a line at given speeds by choosing the left-right chase order with the smallest total time.	Medium7	Dynamic programmingMath	No attempts yet	5s	512 MB	Judgeable
Log Set (Small)Reconstruct the original integer multiset from the frequencies of all its subset sums, breaking ties by sorted order.	Medium7	BacktrackingSorting+1	No attempts yet	5s	512 MB	Judgeable
River Flow (Large)Decide whether recorded daily river flows match constant streams plus diversions that toggle every power of two days up to D, with the fewest farmers.	Medium7	Bit manipulationGreedy+1	No attempts yet	5s	512 MB	Judgeable
Kiddie PoolChoose on-off times for sources with different flow rates and temperatures to collect exactly V liters at temperature X in the least time.	Medium7	Binary searchGreedy+1	No attempts yet	5s	512 MB	Judgeable
Kiddie PoolChoose when to run each hot or cold source so the pool holds exactly V liters at temperature X in the shortest time.	Medium7	Binary searchGreedy+1	No attempts yet	5s	512 MB	Judgeable
English and French (Large)Given one known English sentence, one known French sentence and sentences each wholly in one language, minimize the number of words used in both.	Medium7	Graph	No attempts yet	5s	512 MB	Judgeable
BrattleshipCompute the fewest guesses that guarantee sinking a hidden horizontal ship against an adversary who relocates it within past answers.	Medium7	Game theoryGreedy+1	No attempts yet	5s	512 MB	Judgeable
Less Money, More ProblemsGiven a per-denomination coin limit C and existing denominations, find the fewest new denominations needed so every price up to V is payable.	Medium7	GreedyMath	No attempts yet	5s	512 MB	Judgeable
Counter Culture (Large)Starting from 1, reach N with steps of adding 1 or reversing decimal digits, using the fewest spoken numbers.	Medium7	GreedyMath	No attempts yet	5s	512 MB	Judgeable
Noisy Neighbors (Large)Place N tenants on an R by C grid to minimize the number of shared walls between occupied neighbors.	Medium7	CombinatoricsGreedy+1	No attempts yet	5s	512 MB	Judgeable
Hiking Deer (Small1)Plan one clockwise lap with free speed control so the deer meets the constant-speed circling hikers as few times as possible.	Medium7	GreedyMath+1	No attempts yet	5s	512 MB	Judgeable
LoggingFor each of up to 15 points, find the fewest points to remove so that the point lies on the convex hull of the rest.	Medium7	GeometryBrute force	No attempts yet	5s	512 MB	Judgeable
Logging (Large)For each of N points, report the smallest number of points to remove so it lies on the convex hull.	Medium7	Geometry	No attempts yet	15s	512 MB	Judgeable
Dijkstra (Large)Given a short string of i, j and k repeated X times, decide whether it splits into three nonempty parts that multiply to i, j and k under quaternion rules.	Medium7	MathSimulation	No attempts yet	5s	512 MB	Judgeable
Card GameBob repeatedly deletes three neighboring cards whose values form an arithmetic progression with difference K, and seeks the fewest cards that can remain.	Medium7	Dynamic programmingIntervals	No attempts yet	5s	512 MB	Judgeable
Card Game (Large)Repeatedly delete neighboring triples in arithmetic progression with difference K to leave as few cards as possible.	Medium7	Dynamic programmingIntervals	No attempts yet	5s	512 MB	Judgeable
Symmetric Trees (Large)Decide whether a color-painted tree can be drawn in the plane with a vertical line of symmetry.	Medium7	TreeRecursion+2	No attempts yet	5s	512 MB	Judgeable
Paradox Sort (Large)Given every pairwise candy preference, decide whether some hand-over order leaves Vlad holding candy A and output the lexicographically smallest such order.	Medium7	GraphDFS+1	No attempts yet	5s	512 MB	Judgeable
Allergy Testing (Small)Kelly plans pooled food tests with different waits after negative and positive results to find her single allergy trigger in the fewest worst-case days.	Medium7	Dynamic programming	No attempts yet	5s	512 MB	Judgeable
Allergy Testing (Large)Find the shortest worst-case schedule of pooled food tests with asymmetric wait times that identifies the single allergen.	Medium7	Dynamic programmingBinary search+1	No attempts yet	90s	512 MB	Judgeable
ARAM (Small)Decide when to spend a capped, regenerating reroll budget on fresh random champions to maximize the long-run share of games won.	Medium7	Dynamic programmingProbability+1	No attempts yet	5s	512 MB	Judgeable
Don't Break the Nile (Small)Find the largest flow from the south edge to the north edge of a rectangular grid where rectangle buildings block cells.	Medium7	GraphMatrix	No attempts yet	5s	512 MB	Judgeable
Reordering Train Cars (Small)Count the orders of the given letter strings whose concatenation keeps every equal letter in one contiguous block.	Medium7	GraphCombinatorics+1	No attempts yet	5s	512 MB	Judgeable
Reordering Train Cars (Large)Count the orders of the given strings that keep all equal letters contiguous without reversing any string, modulo 1,000,000,007.	Medium7	GraphCombinatorics+1	No attempts yet	5s	512 MB	Judgeable
Enclosing Grid PointsPlace the fewest stones on an N by M grid so at least K points either hold a stone or cannot reach the border without crossing a stone.	Medium7	GeometryMath+1	No attempts yet	5s	512 MB	Judgeable
New Lottery Game (Large)Count pairs x below A and y below B whose bitwise AND is below K for up to 100 test cases.	Medium7	Dynamic programmingBit manipulation	No attempts yet	5s	512 MB	Judgeable
Full Binary Tree (Large)Delete as few vertices as possible from a given tree so the survivors form a full binary tree with a freely chosen root.	Medium7	Dynamic programmingTree+1	No attempts yet	5s	512 MB	Judgeable
Minesweeper MasterPlace M mines on an R by C grid so one click on the top-left cell reveals every mine-free cell, or report that no such board exists.	Medium7	ImplementationSimulation	No attempts yet	5s	512 MB	Judgeable
Minesweeper MasterYou place M mines on an R by C board so a single corner click reveals every safe cell, or report that no such board exists.	Medium7	ImplementationMatrix	No attempts yet	5s	512 MB	Judgeable
Spaceship Defence (Large)Soldiers teleport free between same-color rooms and ride directed timed turbolifts; each query asks the fastest time from its start room to its destination.	Medium7	Shortest pathGraph	No attempts yet	5s	512 MB	Judgeable
Hamiltonian CircuitInsert vertices one by one into a directed cycle in a tournament by the two given rules, and print -1 when no rule applies.	Medium7	GraphSimulation	No attempts yet	1.5s	512 MB	Judgeable
Graduation Requirements (Large)Choose entry time and intersection to drive clockwise as long as possible without ever occupying the same point as any recorded counterclockwise car.	Medium7	IntervalsMath+1	No attempts yet	5s	512 MB	Judgeable
Drummer (Small)Given integer strike times, find the smallest maximum deviation from any arithmetic progression and print it as a reduced fraction.	Medium7	MathBrute force	No attempts yet	5s	512 MB	Judgeable
Drummer (Large)You choose a start time and beat gap so the worst deviation of the recorded strikes from the ideal beats is as small as possible.	Medium7	Binary searchGeometry+1	No attempts yet	5s	512 MB	Judgeable
X Marks the Spot (Small)Decide whether two perpendicular lines split 4N mines into four groups of N and print the lexicographically smallest grouping.	Medium7	GeometryBrute force	No attempts yet	5s	512 MB	Judgeable
Can't Stop (Large)Find the longest run of consecutive roll sets where every set contains at least one of k chosen numbers.	Medium7	Sliding windowBacktracking	No attempts yet	30s	512 MB	Judgeable
Let Me Tell You a Story (Small)Count the firing orders that delete ministers until the remaining pay sequence never rises down the ranks, modulo 10007.	Medium7	Dynamic programmingCombinatorics	No attempts yet	5s	512 MB	Judgeable
Rigged RouletteSplit integer bets within budget B across 37 roulette numbers, where the ball lands on a least-backed number, to maximize expected payout minus cost.	Medium7	GreedySorting+2	No attempts yet	5s	512 MB	Judgeable
Are We Lost Yet? (Small)In a directed graph with interval edge lengths, test each prefix of a suggested 1 to 2 route and report the first edge that cannot start a shortest path.	Medium7	Shortest pathGraph+1	No attempts yet	5s	512 MB	Judgeable
Are We Lost Yet? (Large)Check each route of a given path in a graph with interval edge lengths and report the first one that cannot lie on a shortest path from city 1 to city 2.	Medium7	Shortest pathGreedy	No attempts yet	5s	512 MB	Judgeable
Observation WheelRandom arrivals fill the free gondolas of a circular wheel, and you compute the expected total of the distance-based fares.	Medium7	Dynamic programmingProbability+1	No attempts yet	5s	512 MB	Judgeable
Ticket Swapping (Small)Given rider groups traveling between stations on one line, compute the largest fare loss from riders swapping entry cards, modulo 1000002013.	Medium7	GreedyStack+1	No attempts yet	5s	512 MB	Judgeable
Many Prizes (Small)For a Swiss-style tournament of 2^N ranked teams with P prizes, report the worst-ranked team guaranteed a prize and the worst-ranked team that can earn one.	Medium7	CombinatoricsGreedy	No attempts yet	5s	512 MB	Judgeable
Erdős and Szekeres Sequence ReconstructionRebuild the lexicographically smallest permutation of 1 to N whose increasing and decreasing subsequence lengths match the given arrays.	Medium7	BacktrackingGreedy+1	No attempts yet	5s	512 MB	Judgeable
Erdős-Szekeres (Large)Given the per-position increasing and decreasing subsequence lengths, print the lexicographically smallest permutation of 1 to N that produces them.	Medium7	GreedySorting	No attempts yet	5s	512 MB	Judgeable
Pogo StickReach (X, Y) with jumps of length 1, 2, and so on in four directions using the fewest jumps, breaking ties by alphabetical order.	Medium7	MathGreedy	No attempts yet	5s	512 MB	Judgeable
Pogo (Large)Reach the target point with jumps of lengths 1 to m in the four cardinal directions using the fewest jumps and the smallest reversed string.	Medium7	MathGreedy	No attempts yet	5s	512 MB	Judgeable
Garbled EmailSplit the garbled string into dictionary words with changed letters spaced at least 5 apart while changing as few letters as possible.	Medium7	Dynamic programmingTrie+1	No attempts yet	60s	512 MB	Judgeable
The Number TrickGiven K observed subset products, find the most likely hidden multiset of N numbers from 2 to M under the given posterior score.	Medium7	Brute forceCombinatorics+1	No attempts yet	5s	1536 MB	Judgeable
Opening the Treasure ChestsOpen all N chests in the lexicographically smallest order with single-use typed keys taken from other chests, or report IMPOSSIBLE.	Medium7	GreedyGraph+1	No attempts yet	5s	512 MB	Judgeable
Professor Normal (Small2)Simulate marble exchanges on an M by N grid where each child splits 12 marbles among live neighbors and children with few marbles drop out.	Medium7	SimulationGraph+1	No attempts yet	5s	512 MB	Judgeable
Perfect GameFind the level order that minimizes the expected time to clear every level in one deathless run when any death restarts the run from the first level.	Medium7	GreedyProbability+1	No attempts yet	5s	512 MB	Judgeable
Perfect GameOrder the levels to minimize the expected total play time when any death restarts the run from the first level.	Medium7	GreedySorting+1	No attempts yet	5s	512 MB	Judgeable
Havannah Winning StructuresGiven the cells taken on a hex board in order, name the first move that links two corners, links three edges, or encloses an empty cell.	Medium7	Union-findBFS	No attempts yet	5s	512 MB	Judgeable
Quality Food (Large)Given a budget, a per-delivery fee, and meal prices with shelf lives, find the most consecutive days of one meal a day starting from the first delivery.	Medium7	Binary searchGreedy+1	No attempts yet	5s	512 MB	Judgeable
Swinging WildDecide if vine-to-vine swings with grip limits can carry you from the first vine to the far ledge.	Medium7	GraphBFS+1	No attempts yet	5s	512 MB	Judgeable
Descending in the Dark (Small)Decide for each cave how many grid cells can reach it moving only left, right, or down, and whether one fixed move plan gathers all of them into that cave.	Medium7	BFSGraph+1	No attempts yet	5s	512 MB	Judgeable
Out of gasYou roll down a hill with free brakes and must reach distance D as fast as possible without ever passing a lead car whose positions are given at sample times.	Medium7	GreedyMath+1	No attempts yet	5s	512 MB	Judgeable
Out of Gas (Large)Brake a car rolling downhill under gravity to reach distance D as fast as possible without ever passing the lead car.	Medium7	GreedyMath+1	No attempts yet	5s	512 MB	Judgeable
Box Factory (Large)Match boxes and toys of equal type in order on run-length encoded lines to maximize the number of pairs.	Medium7	Dynamic programmingString matching	No attempts yet	5s	512 MB	Judgeable
Tide Goes In, Tide Goes Out (Small)Find the earliest reach time to an exit on a height map where water falls 10 cm/s and each move takes 1 second when the exit square has at least 20 cm of water else 10 seconds.	Medium7	Shortest pathGraph+1	No attempts yet	5s	512 MB	Judgeable
Cruise Control (Small)Cars on two lanes hold fixed speeds and may change lanes freely, so decide if all can drive forever or report the latest moment a slowdown is forced.	Medium7	Brute forceSimulation	No attempts yet	5s	512 MB	Judgeable
Cruise Control (Large)Decide whether cars with fixed speeds on a two-lane road can change lanes to avoid collisions forever, and otherwise report the latest safe time as a fraction.	Medium7	GraphSorting+2	No attempts yet	5s	512 MB	Judgeable
Street Tree Props (Large)Assign one or two sticks to each of N trees so every tree reaches support B while the total used force is as small as possible.	Medium7	GreedySorting+1	No attempts yet	5s	512 MB	Judgeable
Sunlight (Large)Each building holds houses along its full height and the sun crosses a semicircle, so the task asks what fraction of houses sees the sun for at least H hours.	Medium7	GeometryIntervals+1	No attempts yet	10s	512 MB	Judgeable
Breaking Windows (Small)M workers randomly reinforce K windows and N villains randomly throw one stone each, and the task asks for the probability that at least one window breaks.	Medium7	ProbabilityCombinatorics+1	No attempts yet	5s	512 MB	Judgeable
Breaking Windows (Large)Compute the chance that random stone throws break at least one of K windows after random reinforcements raise their durability.	Medium7	ProbabilityCombinatorics+1	No attempts yet	30s	512 MB	Judgeable
Battlefield (Large)You reorder your three weapon groups against the fixed enemy line to maximize the summed duel scores.	Medium7	Brute forceMath	No attempts yet	5s	512 MB	Judgeable
Yut Nori Board Check (Small)Decide whether the recorded throw sequence can produce the given board under the stated Yut Nori movement, capture, and shortcut rules.	Medium7	BacktrackingSimulation+1	No attempts yet	5s	512 MB	Judgeable
Bacteria (Small)Pick the largest set of grid rooms with no two rooms on consecutive floors sharing a cell position.	Medium7	GraphBFS+1	No attempts yet	5s	512 MB	Judgeable
Bacteria (Large)Pick the most rooms so no two picked rooms share a cell position on consecutive floors.	Medium7	GraphBFS+1	No attempts yet	5s	512 MB	Judgeable
Survivor (Large)Eat foods in expiry order so each meal starts before it spoils and the next meal follows after its satiation time to maximize total survival time.	Medium7	Dynamic programmingGreedy+1	No attempts yet	10s	512 MB	Judgeable
Market Board (Large)Free dice land on uniform random faces and each cell scores by the longest run of two to four equal faces covering it; find the expected total.	Medium7	ProbabilityCombinatorics	No attempts yet	5s	512 MB	Judgeable
Children Wearing Hats (Small)Given hat totals, child count, and which child first knew its hat color, count the matching colorings modulo 32749.	Medium7	Game theoryDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
Restoring the Erased Equation (Large)Fill every ? with a digit so the addition or subtraction holds without leading zeros and the whole equation is lexicographically smallest.	Medium7	Dynamic programmingGreedy+1	No attempts yet	5s	512 MB	Judgeable
Bacteria Growth (Small)Apply the map x to x^x exactly B times starting from A and report the result modulo C.	Medium7	Number theoryRecursion	No attempts yet	5s	512 MB	Judgeable