Problems

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Total results29,417 problems

Painting the Board
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
SW Skill Test
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Robert Floyd
Medium6
Geometry, Simulation+1
No attempts yet
Time limit
1.2s
Memory limit
256 MB
Judgeable
Kurt Gödel
Medium6
Number theory, Brute force+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Marble Escape 2
Medium6
BFS, Simulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Manhattan Positioning System
Medium6
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Programming Tutors
Medium6
Binary search, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Safe Racing
Medium6
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Digital Addition
Medium6
Implementation, Brute force+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Folding a Rectangle
Medium6
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Jetpack
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Sea Dragons
Medium6
Implementation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dolphins
Medium6
Geometry, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Macbeth
Medium6
Intervals, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Word Puzzle 2
Medium6
DFS, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maximum XOR of two numbers
Medium6
Bit manipulation, Trie
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number of good substrings
Medium6
String, Hash map+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gift Before Tax
Medium6
Binary search, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Compiler
Medium6
Dynamic programming, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Elegant Showroom
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Devil's Sequence
Medium6
Math, Number theory+1
No attempts yet
Time limit
0.5s
Memory limit
64 MB
Judgeable
Spheres and queries
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
Knight Moves to a Corner
Medium6
Dynamic programming, Matrix+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Flipping Coins 3
Medium6
Bit manipulation, Brute force+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Martian Volleyball
Medium6
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Go--
Medium6
Prefix sum, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Mosaic tiles
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Unstacking Boxes
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Even Number of Tolls
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Spiral
Medium6
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Zak Galou
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Teleportation
Medium6
Matrix, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Consistent Letter Path
Medium6
BFS, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lines of Containers
Medium6
Sorting, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Buses and Minibuses
Medium6
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Halting Problem
Medium6
Simulation, Recursion+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cards
Medium6
Dynamic programming, Game theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lost in the Night
Medium6
Probability, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fighting cancer
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alien Ribonucleic Acid
Medium6
Dynamic programming, Intervals
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Parking Lot
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Incident in Atlantis
Medium6
Geometry, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cash Book
Medium6
Dynamic programming, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Route Detour
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Musical Plagiarism
Medium6
String matching, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Come and Go
Medium6
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lightning Strike
Medium6
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cell phone towers
Medium6
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Linear Feedback Shift Register
Medium6
Bit manipulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Set
Medium6
Combinatorics, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Friends or Enemies?
Medium6
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Space Manager
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Swimming Pool
Medium6
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Survival Probability of a Water Flea
Medium6
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Circle Containing All Points
Medium6
Geometry, Brute force
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
XOR Sum 3
Medium6
Bit manipulation, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Common Subsequence of Two Permutations
Medium6
Dynamic programming, Binary search
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tavan
Medium6
Combinatorics, Greedy+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Recover the Alphabet Order
Medium6
Topological sort, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Construction Toy
Medium6
Geometry, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Around and Around We Go
Medium6
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Windy Path
Medium6
Geometry, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Painting the fence
Medium6
Sorting, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Zigzag Subsequence
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Barbells
Medium6
Brute force, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Banking II
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Earl's Extremely Efficient Encryption
Medium6
Array, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Flipping Switches
Medium6
Simulation, Greedy+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Robot Arm Inverse Kinematics
Medium6
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pokemon Identification System
Medium6
Dynamic programming, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Infinity Maze
Medium6
Simulation, Math
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Step Step Evolution
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Safe Area
Medium6
Geometry, Implementation
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Eleven Lover
Medium6
Math, Prefix sum+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Headstrong Student
Medium6
Math, Number theory+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Optimal Rest
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
So Sleepy
Medium6
Graph, Shortest path+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Lying about your age
Medium6
Number theory, Dynamic programming+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Rock Man
Medium6
Graph, Greedy+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Area between a lattice path and its chord
Medium6
Geometry, Prefix sum+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
University Rankings
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Tiling Polygons
Medium6
Backtracking, Recursion+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Marathon
Medium6
Stack, Simulation+2
No attempts yet
Time limit
0.2s
Memory limit
256 MB
Judgeable
Kill the Werewolf
Medium6
Greedy, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Big Bang
Medium6
Number theory, Combinatorics
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Commute
Medium6
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Gold snack sticks on Cebu
Medium6
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Building Uppercase Sentences
Medium6
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Finding a House
Medium6
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Alien Creature Numbering
Medium6
Combinatorics, Tree+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hide and Seek 4
Medium6
BFS, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rotating Display
Medium6
Simulation, Matrix+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fence
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Suspicious Samples
Medium6
Sliding window, Queue+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Exam Redistribution
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hamiltonian Hypercube
Medium6
Bit manipulation, Recursion+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pohlepko
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Emptying the Glasses
Medium6
Dynamic programming, Graph+2
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Free Figurines
Medium6
Tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Lost Logic
Medium6
Graph, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Painting the BoardGiven a grid picture of black and white squares, find the minimum number of horizontal or vertical strokes that paint exactly the required black squares.	Medium6	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
SW Skill TestPick and order problems within T minutes, each solved back to back, to maximize the sum of M_i - (start minute) * P_i.	Medium6	Dynamic programmingSorting+1	No attempts yet	2s	512 MB	Judgeable
Robert FloydStitches walks up to 2048 unit steps on a huge grid, leaving bile on each edge crossed, and you must count the regions the bile walls split the map into.	Medium6	GeometrySimulation+1	No attempts yet	1.2s	256 MB	Judgeable
Kurt GödelGiven a word length, a prime p, and a remainder r, find all words whose Godel number has length i and leaves remainder r mod p.	Medium6	Number theoryBrute force+1	No attempts yet	10s	512 MB	Judgeable
Marble Escape 2Find the minimum number of tilts that roll the red marble into the hole while the blue marble never falls in.	Medium6	BFSSimulation+1	No attempts yet	2s	512 MB	Judgeable
Manhattan Positioning SystemGiven beacons with known grid positions and Manhattan distances to an unknown receiver, decide whether the receiver position is unique, ambiguous, or impossible.	Medium6	GeometryMath+1	No attempts yet	2s	512 MB	Judgeable
Programming TutorsGiven N students and N tutors in a Manhattan-metric city, find the smallest K such that every student can be matched with a distinct tutor at distance at most K.	Medium6	Binary searchGraph+2	No attempts yet	2s	512 MB	Judgeable
Safe RacingCount binary circular arrangements of L booths where every S consecutive booths contain at least one marshal, modulo 123456789.	Medium6	CombinatoricsDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Digital AdditionGiven a black and white picture formed by stacking three seven-segment digit rows, find the lexicographically smallest digit addition that could have produced it.	Medium6	ImplementationBrute force+1	No attempts yet	2s	256 MB	Judgeable
Folding a RectangleEach fold reduces one side to max(x, L-x). Find the fewest folds to turn sides W, H into w, h, in any orientation, or report -1.	Medium6	MathNumber theory+1	No attempts yet	2s	256 MB	Judgeable
JetpackFind the lexicographically smallest schedule of screen holds that moves Barry right across N columns through a 10-row grid while avoiding obstacles.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	64 MB	Judgeable
Sea DragonsCount how many connected groups in a picture match a given sample shape scaled by an integer factor, with no extra or missing cells.	Medium6	ImplementationBrute force+2	No attempts yet	2s	512 MB	Judgeable
DolphinsSimulate fish that swim one unit away from a dolphin each step, and count how many trajectories hit the net polygon.	Medium6	GeometrySimulation+2	No attempts yet	2s	512 MB	Judgeable
MacbethGiven n time intervals and w witches, each witch predicts a chain of non-overlapping intervals, so find the maximum number of intervals coverable by w chains.	Medium6	IntervalsGreedy+1	No attempts yet	2s	512 MB	Judgeable
Word Puzzle 2Given a 5x5 letter grid and up to 20000 dictionary words, count how many words can be traced through adjacent cells without reusing a cell.	Medium6	DFSBacktracking+1	No attempts yet	2s	128 MB	Judgeable
Maximum XOR of two numbersGiven N non-negative integers, find the maximum XOR over all pairs of distinct elements.	Medium6	Bit manipulationTrie	No attempts yet	2s	512 MB	Judgeable
Number of good substringsCount how many distinct substrings of s contain at most k bad letters, counting equal substrings once.	Medium6	StringHash map+1	No attempts yet	2s	512 MB	Judgeable
Gift Before TaxGiven progressive tax bands and each friend's prior income, find the smallest pre-tax gift that leaves the friend with exactly the required after-tax amount.	Medium6	Binary searchMath+1	No attempts yet	2s	512 MB	Judgeable
CompilerPrint the specific 40-instruction-bounded program that displays N on a one-register display, following the stated decomposition rule.	Medium6	Dynamic programmingMath+1	No attempts yet	2s	512 MB	Judgeable
Elegant ShowroomA car on a grid needs a path to a border door; every car cell on the path must be moved, so find the path with the fewest car cells.	Medium6	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Devil's SequenceCompute x_n = (x_{n-1}+x_{n-2})/2 with x_0=0, x_1=1, and count consecutive leading 6s after the decimal point.	Medium6	MathNumber theory+1	No attempts yet	0.5s	64 MB	Judgeable
Spheres and queriesGiven N points in 3D and M spheres, answer for each sphere how many points lie inside it, counting boundary points.	Medium6	GeometrySorting+2	No attempts yet	20s	512 MB	Judgeable
Knight Moves to a CornerCount knight walk sequences of length at most k starting from a board corner and ending on any corner of a 2n x 2n board, modulo 1000007.	Medium6	Dynamic programmingMatrix+1	No attempts yet	5s	512 MB	Judgeable
Flipping Coins 3Flip whole rows or columns of an N by M grid of coins to leave as few tails as possible, with N at most 20.	Medium6	Bit manipulationBrute force+1	No attempts yet	5s	512 MB	Judgeable
Martian VolleyballGiven an axis-parallel polygon, find the minimum number of points outside the court such that every side has a point on its supporting line.	Medium6	GeometryGraph+2	No attempts yet	1s	512 MB	Judgeable
Go--Given a board with black and white stones, count the square sub-areas that contain stones of only one color and report the two totals.	Medium6	Prefix sumMatrix+1	No attempts yet	1s	512 MB	Judgeable
Mosaic tilesGiven an H by L grid with holes (0), fill every hole with one chosen color so that the smallest connected monochromatic region is as large as possible, and report that size.	Medium6	GraphUnion-find+2	No attempts yet	1s	512 MB	Judgeable
Unstacking BoxesBoxes sit in piles in a row; a box can be removed only when it is on top and at least one side is unblocked. Find the fewest removals needed to expose box 1.	Medium6	Dynamic programmingGreedy+1	No attempts yet	1s	512 MB	Judgeable
Even Number of TollsFind the cheapest walk from city 1 to city C in a weighted undirected graph where the number of edges traversed (tolls paid) must be even, counting repeated edges each time.	Medium6	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
SpiralPlace B beans in a clockwise inward spiral on an N by N board and report the row and column of the B-th bean.	Medium6	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Zak GalouFind the cheapest path from room 1 to room N in an undirected graph, where entering or leaving a room costs the minimum mana to kill all monsters living there.	Medium6	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
TeleportationCount length-L button sequences that move from ship S to ship T, where each ship has four outgoing transitions, modulo 10^4.	Medium6	MatrixDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Consistent Letter PathFind the shortest path on an N by N letter grid from top-left to bottom-right where no letter appears in both lowercase and uppercase along the path.	Medium6	BFSBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Lines of ContainersGiven a scrambled L by C grid of distinct numbers, find the fewest whole-row and whole-column swaps that restore the ordered target layout, or report that it is impossible.	Medium6	SortingMatrix+2	No attempts yet	2s	512 MB	Judgeable
Buses and MinibusesGiven a total line length N, count ordered sequences of 10-meter buses and 5-meter minibuses with K minibus colors and L bus colors, and print the last six digits.	Medium6	CombinatoricsDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
The Halting ProblemGiven a small register program that may call itself recursively, decide whether it halts on the input and output the returned value, or print * if it runs forever.	Medium6	SimulationRecursion+1	No attempts yet	2s	512 MB	Judgeable
CardsGiven an even row of cards with integers, two players alternately take an end card; the first player maximizes his total sum while the second minimizes it. Report the best score the first player can guarantee.	Medium6	Dynamic programmingGame theory+2	No attempts yet	2s	512 MB	Judgeable
Lost in the NightOn a tree, a walker starting at node A repeatedly picks a uniformly random neighbor until reaching hotel B or C; find the probability of hitting B first.	Medium6	ProbabilityGraph+2	No attempts yet	2s	512 MB	Judgeable
Fighting cancerGiven two trees on atoms 1..N, decide whether they are isomorphic as unlabeled graphs and print S or N.	Medium6	TreeDFS+1	No attempts yet	2s	512 MB	Judgeable
Alien Ribonucleic AcidFor each strand, compute the largest number of base pairs (B-S and C-F) that can form when disjoint intervals fold onto themselves.	Medium6	Dynamic programmingIntervals	No attempts yet	2s	512 MB	Judgeable
Parking LotSimulate a single-line parking lot where each arriving vehicle takes the first free gap from the entrance that fits, and total the fees for vehicles that park.	Medium6	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Incident in AtlantisGiven line-segment walls, up to 50 booths, and a teleport budget T, find the shortest walk from start to portal where teleports happen only between booths with an unobstructed segment.	Medium6	GeometryShortest path+2	No attempts yet	2s	512 MB	Judgeable
Cash BookGiven N amounts and a signed total F, decide for each amount whether it is forced to be added, forced to be subtracted, or free, over all sign choices summing to F.	Medium6	Dynamic programmingBacktracking+2	No attempts yet	2s	512 MB	Judgeable
Route DetourFind the cheapest route from a repaired vehicle's city to the destination, where any first contact with the fixed route forces the rest of the trip to follow that route exactly.	Medium6	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Musical PlagiarismGiven a song as a sequence of notes and a suspect excerpt, decide whether the excerpt appears in the song under some transposition (key change).	Medium6	String matchingArray+2	No attempts yet	2s	512 MB	Judgeable
Come and GoGiven a mixed graph of one-way and two-way streets, decide whether every pair of intersections is mutually reachable.	Medium6	GraphDFS+1	No attempts yet	2s	512 MB	Judgeable
Lightning StrikeFor each test case, compute the area of a circle cut by an infinite wedge with a given apex, direction, and spread angle.	Medium6	GeometryMath+1	No attempts yet	2s	512 MB	Judgeable
Cell phone towersGiven up to 40 house coordinates, find the smallest common radius so that two circles of that radius can cover every house.	Medium6	GeometryBinary search+1	No attempts yet	2s	512 MB	Judgeable
Linear Feedback Shift RegisterGiven an N-bit linear feedback shift register, its taps, and two states, find the minimum number of clock pulses to reach the final state, or report that it is impossible.	Medium6	Bit manipulationMath+1	No attempts yet	2s	512 MB	Judgeable
SetGiven multiset of cards, each with a count of figures (1 to 3) and a shape (circle, square, triangle), find the maximum number of disjoint triples where each characteristic is all-same or all-different.	Medium6	CombinatoricsGreedy+1	No attempts yet	2s	512 MB	Judgeable
Friends or Enemies?For each query number pair, find the points on a clockwise square spiral, then check whether they lie on the same side of a given line.	Medium6	GeometryMath+1	No attempts yet	2s	512 MB	Judgeable
Space ManagerSimulate a disk with insert, remove, and compact operations using best-fit placement, then print an eight-block free-space picture or a full-disk error.	Medium6	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Swimming PoolGiven pool dimensions and limited stocks of three tile sizes, find the cheapest whole-tile covering of the floor and four walls, or report impossibility.	Medium6	GreedyMath+1	No attempts yet	2s	512 MB	Judgeable
Survival Probability of a Water FleaCount the paths of length n on a line starting at k that never return to 0, so the survivor count is S in S/2^n.	Medium6	CombinatoricsDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
Circle Containing All PointsGiven N points, find the diameter of the smallest enclosing circle, printed to two decimals.	Medium6	GeometryBrute force	No attempts yet	2s	512 MB	Judgeable
XOR Sum 3Compute the XOR of every contiguous subsequence of A and print the sum of all those XOR values.	Medium6	Bit manipulationPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
Longest Common Subsequence of Two PermutationsTwo permutations of 1 to N are given; find the length of their longest common subsequence.	Medium6	Dynamic programmingBinary search	No attempts yet	2s	512 MB	Judgeable
TavanGiven a pattern with # placeholders, each replaced by one of K given letters, find the Xth resulting string in alphabetical order.	Medium6	CombinatoricsGreedy+2	No attempts yet	1s	32 MB	Judgeable
Recover the Alphabet OrderGiven words claimed to be lexicographically sorted, decide whether the letter order is unique, impossible, or ambiguous.	Medium6	Topological sortGraph+1	No attempts yet	2s	512 MB	Judgeable
Construction ToyGiven up to nine distinct segment lengths, find the largest possible distance from a wall reachable by gluing triangles onto an initial base segment.	Medium6	GeometryBacktracking+1	No attempts yet	2s	512 MB	Judgeable
Around and Around We GoLay out two voices of a song as a round, aligning each voice's symbols so that simultaneous sounds share a column and gaps print as plus signs.	Medium6	SimulationImplementation+1	No attempts yet	2s	512 MB	Judgeable
Windy PathGiven N points and a string of L/R turns, build the non-crossing path by repeatedly picking the unused point that is extreme (leftmost or rightmost) relative to the last point.	Medium6	GeometryGreedy+2	No attempts yet	2s	512 MB	Judgeable
Painting the fencePick a pairwise non-overlapping set of intervals to cover as many of the n slats as possible, then report the number left unpainted.	Medium6	SortingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Longest Zigzag SubsequenceFind the length of the longest subsequence whose adjacent comparisons strictly alternate between up and down.	Medium6	Dynamic programmingGreedy	No attempts yet	2s	512 MB	Judgeable
BarbellsGiven up to 14 bars and 14 plates, find every total weight obtainable by putting plates on both sides of one bar so that the two sides balance.	Medium6	Brute forceHash map+2	No attempts yet	2s	512 MB	Judgeable
Banking IIGiven a PIN and a leftover lowercase pattern, insert uppercase skips so the letter values sum to the PIN length, maximizing the extracted digit sum.	Medium6	Dynamic programmingGreedy	No attempts yet	1s	512 MB	Judgeable
Earl's Extremely Efficient EncryptionGiven a growing set of stored image indices, find the longest run of consecutive unmarked indices below each query length w_j.	Medium6	ArraySorting+2	No attempts yet	2s	512 MB	Judgeable
Flipping SwitchesSimulate the given local-search procedure: repeatedly flip the lowest-numbered switch that increases the number of shining lights, then print the final setting.	Medium6	SimulationGreedy+2	No attempts yet	7s	512 MB	Judgeable
Robot Arm Inverse KinematicsGiven segment lengths and a target hand position for a robot arm with equal joint angles, recover the base angle and joint angle that reach it.	Medium6	GeometryBinary search+1	No attempts yet	2s	512 MB	Judgeable
Pokemon Identification SystemWith a budget B, buy k_f agents for each feature (k_f >= 1) to maximize the product of 1-(1-r_f)^k_f, and report the smallest optimal cost.	Medium6	Dynamic programmingMath+1	No attempts yet	2s	512 MB	Judgeable
Infinity MazeSimulate a robot that walks a walled grid, turning right at obstacles, for up to 10^18 forward moves, and report where it stops.	Medium6	SimulationMath	No attempts yet	8s	512 MB	Judgeable
Step Step EvolutionGiven a sequence of dance-pad arrows, find the minimum number of adjacent pairs pressed by the same foot, respecting the left/right column rule.	Medium6	Dynamic programmingGreedy+2	No attempts yet	8s	512 MB	Judgeable
Safe AreaGiven a rectangular screen, circular machine radius, and laser lines with thickness, decide if some circle center avoids all beams.	Medium6	GeometryImplementation	No attempts yet	8s	512 MB	Judgeable
Eleven LoverFor each number given as a digit string, count its substrings with no leading zero that are divisible by 11.	Medium6	MathPrefix sum+1	No attempts yet	8s	512 MB	Judgeable
Headstrong StudentFor each fraction x/y, report how many decimal digits come before the repeating part starts and how long that repeating part is (0 if the decimal terminates).	Medium6	MathNumber theory+2	No attempts yet	8s	512 MB	Judgeable
Optimal RestGiven a sequence of R commands with dotted durations, find the shortest valid equivalent expression, breaking ties by lexicographic order.	Medium6	Dynamic programmingGreedy+2	No attempts yet	8s	512 MB	Judgeable
So SleepyFind the longest total time asleep on one train while traveling from a start station and time to an appointment station by a deadline.	Medium6	GraphShortest path+1	No attempts yet	8s	512 MB	Judgeable
Lying about your ageTrack the smallest claimable value at a real age given a starting claim, where a claim read in some base equals the real age and claims never decrease.	Medium6	Number theoryDynamic programming+1	No attempts yet	8s	512 MB	Judgeable
Rock ManEach tool takes day1 days normally or day2 if its support tool is finished first; order the tools to minimize total days.	Medium6	GraphGreedy+2	No attempts yet	8s	512 MB	Judgeable
Area between a lattice path and its chordGiven a monotone path of up and right steps, compute the total area between the path and the straight chord from start to end.	Medium6	GeometryPrefix sum+2	No attempts yet	8s	512 MB	Judgeable
University RankingsGiven M rankings of N universities, find the longest sequence where each earlier university beats the next in every ranking.	Medium6	Dynamic programmingSorting+1	No attempts yet	8s	512 MB	Judgeable
Tiling PolygonsTile a rectilinear polygon with 1x3 and 3x1 tiles, choosing at each step the lexicographically smallest covering grid.	Medium6	BacktrackingRecursion+2	No attempts yet	8s	512 MB	Judgeable
MarathonGroups at distinct coordinates move right at speed 100/size and merge on contact; simulate until stable and report final sizes left to right.	Medium6	StackSimulation+2	No attempts yet	0.2s	256 MB	Judgeable
Kill the WerewolfFor each player assumed to be the werewolf, decide whether the villagers can outvote him; count the players who still win.	Medium6	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable
Big BangCount the maximum number of distinct particles detectable at lattice points in a 1..N cube, where a particle is a ray from the origin with positive integer velocity components.	Medium6	Number theoryCombinatorics	No attempts yet	1s	512 MB	Judgeable
CommuteGiven a grid of vertical/horizontal blocks and a fixed set of moves, find the fewest steps from any vertical block in row 0 to row R-1.	Medium6	BFSGraph+1	No attempts yet	1s	256 MB	Judgeable
Gold snack sticks on CebuGiven a weighted undirected graph, find the maximum over all routes from s to e of the minimum edge weight on the route.	Medium6	GraphUnion-find+1	No attempts yet	1s	256 MB	Judgeable
Building Uppercase SentencesCount the distinct uppercase sentences you can form by deleting letters and grouping the rest into blocks of three identical letters.	Medium6	Dynamic programmingString	No attempts yet	1s	256 MB	Judgeable
Finding a HouseOn a weighted undirected graph, find the vertex with no McDonald's or Starbucks whose distance to the nearest McDonald's is at most x, to the nearest Starbucks at most y, and whose two distances sum to the minimum.	Medium6	GraphShortest path+1	No attempts yet	1s	256 MB	Judgeable
Alien Creature NumberingCount the labelings of a complete binary tree of height H with 1..2^(H+1)-1 where every parent's label is smaller than its children's labels, modulo 1e9+7.	Medium6	CombinatoricsTree+1	No attempts yet	1s	256 MB	Judgeable
Hide and Seek 4Find the shortest time from N to K using moves -1, +1, and 2X, then output the lexicographically smallest shortest path.	Medium6	BFSGraph+1	No attempts yet	2s	512 MB	Judgeable
Rotating DisplayGiven an N x N grid of arrow-like tokens and a long sequence of rotations and flips, print the grid after applying every command in order.	Medium6	SimulationMatrix+1	No attempts yet	2s	512 MB	Judgeable
FenceOn a small grid with one wolf and several sheep, find the shortest closed fence along grid lines that encloses every sheep and excludes the wolf.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Suspicious SamplesFor each condition, count samples whose value is greater or less than the min, max, or average of samples in the preceding time window.	Medium6	Sliding windowQueue+2	No attempts yet	2s	512 MB	Judgeable
Exam RedistributionFind the lexicographically smallest order to visit rooms so the exam pile never runs out and no room 1 student can end up with their own exam.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Hamiltonian HypercubeGiven two binary strings in Gray Code order, count how many code words lie strictly between them on the n-bit Gray Code path.	Medium6	Bit manipulationRecursion+1	No attempts yet	2s	512 MB	Judgeable
PohlepkoFind the lexicographically smallest string read along a monotone path from the top-left to the bottom-right cell of a grid of lowercase letters.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	64 MB	Judgeable
Emptying the GlassesGiven N glasses and pairwise pour costs, find the minimum effort to end with water in at most K glasses.	Medium6	Dynamic programmingGraph+2	No attempts yet	2s	32 MB	Judgeable
Free FigurinesGiven two valid nesting configurations of n matryoshka dolls, find the minimum number of place and take-out moves to transform one into the other.	Medium6	TreeGreedy+1	No attempts yet	1s	512 MB	Judgeable
Lost LogicGiven three satisfying assignments of n variables, construct a set of at most 500 implication constraints whose only solutions are exactly those three.	Medium6	GraphImplementation+1	No attempts yet	1s	512 MB	Judgeable