Interview warm-up

Short whiteboard warmups

Under construction

Still being built. Things may change

Total results4,880 problems

Packet Routing
Medium4
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Year 2000
Medium4
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
You Can't Get There From Here
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Nasty Numbers
Medium4
Number theory, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Divisibility by 11
Medium4
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
When in Rome...
Medium4
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maximum Distance
Medium4
Array, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Safebreaker
Medium4
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Where's Waldorf?
Medium4
Array, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Recurring Decimals
Medium4
Hash map, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bad Cowtractors
Medium4
Minimum spanning tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Restore the Erased Numbers
Medium4
Brute force, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Grandpa's Lottery Games
Medium4
Array, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Similar Triangles
Medium4
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Milk and Honey
Medium4
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Geocaching Coordinates
Medium4
Brute force, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Walk
Medium4
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Paper Strips
Medium4
Implementation, Array+2
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Meli kalikamaka
Medium4
String, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Daisies and Love
Medium4
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Quantum Computer
Medium4
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Substring Reversal
Medium4
String, Two pointers
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Herb Trees
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Internet
Medium4
Greedy, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rotten Ropes
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Grandpa's Other Estate
Medium4
Array, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maya Calendar
Medium4
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ancient Cipher
Medium4
String, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Decoding Task
Medium4
Bit manipulation, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Chemical Reactions
Medium4
String, Stack+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Disk Tree
Medium4
Trie, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lock Manager
Medium4
Hash map, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Mysterious X Network
Medium4
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bowling
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bukazoids
Medium4
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Filthy Rich
Medium4
Dynamic programming, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Holiday Gifts
Medium4
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Scavenger Hunt
Medium4
Graph, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Numbers With No Repeated Digits
Medium4
Brute force, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
People in the Company
Medium4
Hash map, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
To Eat or Be Eaten
Medium4
Sorting, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hotel
Medium4
Implementation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimum Swaps
Medium4
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sultan's Land
Medium4
Array, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Longest Ordered Subsequence
Medium4
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hansel and Grethel
Medium4
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Canoes
Medium4
Greedy, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
ROT13
Medium4
Hash map, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Restaurants
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Singing
Medium4
Greedy
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Coins
Medium4
Sorting, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Train
Medium4
Greedy, Hash map
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Chochlik
Medium4
Union-find, Graph+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Calendars
Medium4
Prefix sum, Binary search
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bajtozja the Frog
Medium4
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Banquet
Medium4
Graph, DFS
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Drawers
Medium4
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ladder
Medium4
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Matches
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gathering Mushrooms
Medium4
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flipping the Vegetable Garden
Medium4
Prefix sum, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Birthday Party
Medium4
Number theory, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Merchant
Medium4
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Recursive Pattern (Szlaczek)
Medium4
Recursion, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Independent Architecture
Medium4
BFS, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Exam Preparation
Medium4
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Experiment
Medium4
Topological sort, Graph+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Circle Dance
Medium4
Graph, DFS
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Match Maker
Medium4
Simulation, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
DSLR
Medium4
BFS, Graph
No attempts yet
Time limit
6s
Memory limit
256 MB
Judgeable
Dome Stadium
Medium4
Prefix sum
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Escape the Maze with a Drill
Medium4
Shortest path, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Missile Protector
Medium4
Dynamic programming, Binary search
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Guess the Word
Medium4
String, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coins
Medium4
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Oulipo
Medium4
String matching, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Police in a Line
Medium4
Geometry, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Starship Hakodate-maru
Medium4
Brute force, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Single Digit Adder
Medium4
Stack, Recursion
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Job Scheduling by Open Bidding
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mixing Words
Medium4
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Walking While Drinking Beer
Medium4
BFS, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Longest Common Subsequence
Medium4
Dynamic programming
No attempts yet
Time limit
0.1s
Memory limit
256 MB
Judgeable
Privacy Loss
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hoo's Afraid of the Big Bad Wolf?
Medium4
Shortest path, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flood-It
Medium4
Simulation, BFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Digital Video Discs (DVDs)
Medium4
Segment tree
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Fence
Medium4
Shortest path, BFS+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Casino
Medium4
String, String matching
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A site just for programming contests
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Happy Primes
Medium4
Number theory, Hash map+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stickers
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Handing Out Books
Medium4
Greedy, Intervals+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
NASSA's Robot
Medium4
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Longest Balanced Sub-Sequence
Medium4
Prefix sum, Hash map
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Spiral Coordinates
Medium4
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tree Coloring
Medium4
Dynamic programming, Tree+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Diamond Mining Profits
Medium4
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sums of Distinct Natural Numbers
Medium4
Dynamic programming, Combinatorics
No attempts yet
Time limit
7s
Memory limit
128 MB
Judgeable
Magic Multiplying Machine
Medium4
Dynamic programming, Math
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Packet RoutingGiven a tree with weighted edges connecting N computers, compute the travel time along the unique path between each query pair of computers.	Medium4	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Year 2000Read n lines of text and expand the two-digit year in every date that matches one of three fixed formats, leaving all other characters unchanged.	Medium4	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
You Can't Get There From HereSimulate a dot bouncing diagonally inside a rectangular grid with mirror edges; report whether it reaches point B from A and after how many moves.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Nasty NumbersFor each number under 32001, list its factor pairs and check whether the difference of one pair equals the sum of another pair.	Medium4	Number theoryBrute force+2	No attempts yet	1s	128 MB	Judgeable
Divisibility by 11Apply Dodgson's divisibility-by-11 test to numbers up to 50 digits, printing each intermediate value and the final verdict.	Medium4	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
When in Rome...Parse two Roman numerals, add them, and print the sum as a Roman numeral, or CONCORDIA CUM VERITATE when the sum exceeds 1000.	Medium4	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
Maximum DistanceGiven two non-increasing arrays, find the largest j - i such that j >= i and Y[j] >= X[i].	Medium4	ArrayTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
SafebreakerGiven up to 10 guesses with correct-position and wrong-position digit counts, decide whether the secret 4-digit code is unique, impossible, or indeterminate.	Medium4	Brute forceImplementation+2	No attempts yet	1s	128 MB	Judgeable
Where's Waldorf?Given a grid of letters and a list of words, find the first-letter position of each word along any of eight straight directions, or the bottom-right cell if absent.	Medium4	ArrayString+2	No attempts yet	1s	128 MB	Judgeable
Recurring DecimalsFor each (a0, L), iterate the digit-rearrange-and-subtract map until a value repeats, then print the first repeated index j, the repeated value, and the cycle length.	Medium4	Hash mapSimulation+2	No attempts yet	1s	128 MB	Judgeable
Bad CowtractorsGiven an undirected weighted graph, find a spanning tree of maximum total edge cost, or report -1 if no spanning tree exists.	Medium4	Minimum spanning treeGreedy+2	No attempts yet	1s	128 MB	Judgeable
Restore the Erased NumbersSome of the four numbers a, b, a^2 b, ab^2 are replaced by 0; restore the original row, breaking ties toward the lexicographically smallest tuple.	Medium4	Brute forceMath+2	No attempts yet	1s	128 MB	Judgeable
Grandpa's Lottery GamesGiven daily lottery spending and winnings, report the overall profit sign, the single day with the largest loss, and the consecutive run with the largest total loss.	Medium4	ArrayPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Similar TrianglesGiven two triangles by integer vertex coordinates, decide whether they are similar and if so print the squared similarity coefficient as a reduced fraction p/q, else print -1.	Medium4	GeometryMath+2	No attempts yet	1s	1024 MB	Judgeable
Milk and HoneyAssign each field to cows or bees to maximize total happiness, where each field's output value declines linearly with each added unit.	Medium4	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
Geocaching CoordinatesGiven a coordinate formula with placeholder letters and each letter's allowed digit values, print every distinct resulting coordinate in lexicographic order.	Medium4	Brute forceImplementation+1	No attempts yet	1s	1024 MB	Judgeable
WalkParse walking segments given as duration and pace per kilometre, then report total distance in metres and average speed in km/h.	Medium4	ImplementationMath+2	No attempts yet	1s	1024 MB	Judgeable
Paper StripsStrips are glued on a black strip in order, each hiding what lies below; print the visible color and length of each final segment, merging equal neighbors.	Medium4	ImplementationArray+2	No attempts yet	6s	1024 MB	Judgeable
Meli kalikamakaApply syllable and letter substitution rules to convert a lowercase text into a Polynesian-style pronunciation.	Medium4	StringSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Daisies and LoveFind the largest M so that every petal count L_i is congruent to some common value modulo M, where all L_i are multiples of M.	Medium4	MathNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Quantum ComputerGiven a grid with obstacles and a sensor, decide whether a laser from a non-corner edge cell reaches the sensor with zero, one, or more than one mirror.	Medium4	SimulationImplementation	No attempts yet	1s	1024 MB	Judgeable
Substring ReversalGiven an original string and the result of reversing one substring of length at least two, find the reversed segment, preferring the smallest start then end.	Medium4	StringTwo pointers	No attempts yet	1s	1024 MB	Judgeable
Herb TreesPick trees to keep so that no two kept trees are adjacent, maximizing the sum of their berry counts.	Medium4	Dynamic programming	No attempts yet	1s	1024 MB	Judgeable
InternetGiven measurements with connection states, where the first and last show a connection, find the longest possible time the connection could have been down.	Medium4	GreedyImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Rotten RopesGiven the tear-off weights of n ropes, find the maximum object weight that a chosen subset can carry so that no rope in the subset breaks.	Medium4	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Grandpa's Other EstateGiven up to 100 points and a square side length r, place the axis-aligned square to cover as many points as possible, counting border points as inside.	Medium4	ArraySorting+2	No attempts yet	1s	128 MB	Judgeable
Maya CalendarConvert n dates from the Haab calendar to the Tzolkin calendar using modular arithmetic on the day index.	Medium4	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Ancient CipherGiven two equal-length strings of capital letters, decide whether the first can be obtained from the second by a substitution cipher followed by a permutation.	Medium4	StringSorting+2	No attempts yet	2s	128 MB	Judgeable
Decoding TaskGiven an encrypted message and the same message with a space prepended, recover the shared XOR key bytes.	Medium4	Bit manipulationImplementation	No attempts yet	2s	128 MB	Judgeable
Chemical ReactionsParse chemical formulas with nested parentheses and multipliers, then compare element counts between the left side and each candidate right side.	Medium4	StringStack+1	No attempts yet	1s	128 MB	Judgeable
Disk TreeGiven full directory paths, rebuild the tree and print every directory name on its own line, indented by depth, with siblings in ASCII order.	Medium4	TrieSorting+1	No attempts yet	1s	128 MB	Judgeable
Lock ManagerProcess lock requests in order, granting an S or X lock when it conflicts with no granted lock, denying it and blocking the transaction otherwise, and ignoring later requests from blocked transactions.	Medium4	Hash mapSimulation+2	No attempts yet	1s	128 MB	Judgeable
The Mysterious X NetworkGiven an undirected graph of N people, find the minimum number of intermediate people on a shortest path between two given people.	Medium4	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
BowlingGiven the pins knocked down on each delivery of a valid ten-frame bowling game, compute the total score.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
BukazoidsGiven cell counts and a fixed number of single and double jumps, maximize collected bukazoids and output the lexicographically smallest optimal visit sequence.	Medium4	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Filthy RichGiven a grid of gold amounts, find the maximum sum along a path from the top-left to the bottom-right cell, moving only east, south, or south-east.	Medium4	Dynamic programmingMatrix+1	No attempts yet	2s	128 MB	Judgeable
Holiday GiftsAssign one of two priced gifts to each node of a rooted tree so no two adjacent employees share a gift, minimizing total cost.	Medium4	TreeDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Scavenger HuntGiven S-1 ordered pairs of steps from a route of S steps, reconstruct the full sequence of steps in order.	Medium4	GraphHash map+1	No attempts yet	1s	128 MB	Judgeable
Numbers With No Repeated DigitsGiven n up to one million, print the n-th positive integer whose decimal digits are all distinct.	Medium4	Brute forceDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
People in the CompanyGiven access-card records of enter and leave events, list the names of employees who are currently inside the office, sorted in reverse alphabetical order.	Medium4	Hash mapSorting+1	No attempts yet	1s	256 MB	Judgeable
To Eat or Be EatenCount pairs where an A creature is strictly larger than a B creature, given two lists of sizes.	Medium4	SortingTwo pointers+2	No attempts yet	1s	256 MB	Judgeable
HotelFor each team, pick the cheapest hotel in its bed-size category that can hold the team, breaking ties by larger bed size and then input order.	Medium4	ImplementationBrute force+2	No attempts yet	1s	128 MB	Judgeable
Minimum SwapsFor each string of distinct lowercase letters, find the minimum number of arbitrary swaps needed to sort it into alphabetical order.	Medium4	SortingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Sultan's LandGiven P pillars on an N by N grid, count how many sets of four pillars form the corners of an axis-aligned rectangle.	Medium4	ArrayHash map+2	No attempts yet	1s	128 MB	Judgeable
Longest Ordered SubsequenceGiven a sequence of N integers, find the length of the longest non-decreasing subsequence.	Medium4	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Hansel and GrethelGiven two landmarks on a map and the compass bearing from the walkers to each landmark, find the walkers' coordinates.	Medium4	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
CanoesGiven a canoe weight limit and each participant's weight, find the minimum number of two-person canoes needed to carry everyone.	Medium4	GreedyTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
ROT13Given a list of lowercase words, count ordered pairs (w1, w2) from the list where w2 equals the ROT13 encoding of w1.	Medium4	Hash mapString+2	No attempts yet	1s	128 MB	Judgeable
RestaurantsEvery city connects by weighted roads and some hold restaurants; report the largest distance from any city to its closest restaurant.	Medium4	Shortest pathGraph+1	No attempts yet	1s	128 MB	Judgeable
SingingThe task is to place the fewest books so every student in a row has one or sits next to one.	Medium4	Greedy	No attempts yet	1s	512 MB	Judgeable
CoinsCount the ways to place coins of sizes 1 to n into slots with capacities a_i so every coin fits, modulo 1000000007.	Medium4	SortingCombinatorics+1	No attempts yet	1s	512 MB	Judgeable
TrainCount the fewest round trips a train needs to drop its wagons from the back at their assigned cities in order.	Medium4	GreedyHash map	No attempts yet	1s	512 MB	Judgeable
ChochlikDecide for each department whether wheels linked by same-direction and opposite-direction belts can all spin without contradiction.	Medium4	Union-findGraph+1	No attempts yet	1s	512 MB	Judgeable
CalendarsConvert each given date to its day of year with one calendar, then locate the matching month and day in the other calendar.	Medium4	Prefix sumBinary search	No attempts yet	1s	512 MB	Judgeable
Bajtozja the FrogThe frog hops between stones at most s apart starting from stone p and then dives length s to finish as far from the start as possible.	Medium4	GraphBFS+1	No attempts yet	1s	512 MB	Judgeable
BanquetFind how many round tables are needed by counting the cycles in the left-neighbor links.	Medium4	GraphDFS	No attempts yet	1s	512 MB	Judgeable
DrawersPush as few drawers in as possible so the pull-out lengths strictly increase from the top drawer down.	Medium4	GreedyArray	No attempts yet	1s	128 MB	Judgeable
LadderCount the ways to climb s rungs with steps of one or two and report each answer modulo 2^p for up to a million queries.	Medium4	Dynamic programmingMath	No attempts yet	1s	128 MB	Judgeable
MatchesStarting from one match, fire spreads to each neighbor no taller than the burning match, and the task asks for the largest group that can burn.	Medium4	Dynamic programmingArray	No attempts yet	1s	128 MB	Judgeable
Gathering MushroomsChoose the earliest day t of at least 1 that maximizes the total weight of mushrooms still edible, where each weight grows daily.	Medium4	Prefix sumArray	No attempts yet	1s	128 MB	Judgeable
Flipping the Vegetable GardenApply up to one million rectangle flips to an n by n binary garden and print the final layout.	Medium4	Prefix sumMatrix	No attempts yet	1s	128 MB	Judgeable
The Birthday PartyFind the smallest guest count m so that every candy pile leaves at least one leftover when divided equally among m guests.	Medium4	Number theoryArray	No attempts yet	1s	128 MB	Judgeable
MerchantFind the simple path, possibly empty, in a weighted tree whose edge weights sum to the largest value.	Medium4	TreeDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Recursive Pattern (Szlaczek)Given a starting sequence that is repeatedly extended by appending its own reversal, report the value at position M.	Medium4	RecursionArray+1	No attempts yet	1s	128 MB	Judgeable
Independent ArchitectureCount the wall cells plus the empty cells enclosed by the single closed wall loop in each grid.	Medium4	BFSMatrix	No attempts yet	1s	128 MB	Judgeable
Exam PreparationSchedule preparation days before each exam day and find how many days before the earliest exam study must start.	Medium4	GreedySorting	No attempts yet	1s	128 MB	Judgeable
ExperimentOrient each undecided corridor so the whole maze stays acyclic, following the smallest-numbered topological order of the fixed corridors.	Medium4	Topological sortGraph+1	No attempts yet	3s	128 MB	Judgeable
Circle DanceFind the largest want-link cycle in which each girl is disliked by fewer than half of the members.	Medium4	GraphDFS	No attempts yet	1s	128 MB	Judgeable
Match MakerPair N men with N women from full preference lists to output the man-optimal stable matching with no blocking pair.	Medium4	SimulationGreedy	No attempts yet	1s	128 MB	Judgeable
DSLRFind the shortest DSLR command string that turns register value A into target B, breaking ties in alphabetical order.	Medium4	BFSGraph	No attempts yet	6s	256 MB	Judgeable
Dome StadiumChoose the village coordinate that minimizes the total fan-weighted travel distance.	Medium4	Prefix sum	No attempts yet	1s	256 MB	Judgeable
Escape the Maze with a DrillDecide whether a robot can reach the target on a grid by drilling through at most k walls.	Medium4	Shortest pathBFS+2	No attempts yet	1s	128 MB	Judgeable
Missile ProtectorSelect the most missiles that form a non-decreasing height sequence in arrival order.	Medium4	Dynamic programmingBinary search	No attempts yet	1s	128 MB	Judgeable
Guess the WordGiven each uppercase word, output the next distinct arrangement of its letters in dictionary order, or the word itself when it is already last.	Medium4	StringSorting	No attempts yet	1s	128 MB	Judgeable
CoinsCount the unordered combinations of up to 20 coin values that sum to the target amount M.	Medium4	Dynamic programmingCombinatorics	No attempts yet	1s	128 MB	Judgeable
OulipoCount overlapping occurrences of a pattern W in a text T over uppercase letters for each test case.	Medium4	String matchingString	No attempts yet	1s	128 MB	Judgeable
Police in a LineDecide whether any three of up to 300 given points are collinear, repeating for each dataset in the input.	Medium4	GeometryBrute force	No attempts yet	1s	128 MB	Judgeable
Starship Hakodate-maruGiven a limit up to 151200, find the largest amount that splits into a cube plus a tetrahedral number.	Medium4	Brute forceSorting+2	No attempts yet	1s	128 MB	Judgeable
Single Digit AdderEvaluate each line as an arithmetic expression of single digits with plus, minus, and parentheses.	Medium4	StackRecursion	No attempts yet	1s	128 MB	Judgeable
Job Scheduling by Open BiddingPick bids whose total seconds fit the available time so the total payment is as large as possible.	Medium4	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
Mixing WordsDecide whether the third word interleaves the first two words while keeping each word's letter order.	Medium4	Dynamic programmingString	No attempts yet	1s	256 MB	Judgeable
Walking While Drinking BeerDecide whether the festival is reachable when each 20-bottle box allows 1000 meters of Manhattan travel between refills at stores.	Medium4	BFSGraph	No attempts yet	1s	128 MB	Judgeable
Longest Common SubsequenceCompute the length of the longest subsequence shared by two uppercase strings of length up to 1000.	Medium4	Dynamic programming	No attempts yet	0.1s	256 MB	Judgeable
Privacy LossPick a subset of options that maximizes total security benefit without exceeding the money budget and the privacy limit.	Medium4	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
Hoo's Afraid of the Big Bad Wolf?Find the directed path from X to Y with the largest product of edge safety probabilities, printed rounded to six decimals.	Medium4	Shortest pathGraph	No attempts yet	1s	128 MB	Judgeable
Flood-ItSimulate greedy flood fills from the top-left corner that pick the color giving the largest connected region and report moves and per-color counts.	Medium4	SimulationBFS+1	No attempts yet	2s	128 MB	Judgeable
Digital Video Discs (DVDs)The program tracks disc swaps on numbered slots and reports whether slots A to B hold exactly discs A to B.	Medium4	Segment tree	No attempts yet	2s	256 MB	Judgeable
FenceFrom outside the grid, compute every empty cell's minimum fence breaks with 0-1 BFS, then report the largest value and how many cells attain it.	Medium4	Shortest pathBFS+2	No attempts yet	2s	64 MB	Judgeable
CasinoFind every longest palindromic substring of length at least 2 in each string and print them rightmost first.	Medium4	StringString matching	No attempts yet	1s	128 MB	Judgeable
A site just for programming contestsBuy each plot in decreasing price order, one per year, and report the total cost or Too expensive when it exceeds the budget.	Medium4	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
Happy PrimesPrint every number up to n that is both prime and happy, where repeated digit-square sums reach 1, one per line in increasing order.	Medium4	Number theoryHash map+1	No attempts yet	1s	256 MB	Judgeable
StickersPick stickers from a 2 by n grid with no two sharing an edge to maximize the total score.	Medium4	Dynamic programmingArray	No attempts yet	1s	256 MB	Judgeable
Handing Out BooksAssign each applicant at most one distinct book numbered within their requested interval to maximize the number of satisfied applicants.	Medium4	GreedyIntervals+1	No attempts yet	2s	256 MB	Judgeable
NASSA's RobotYou get a walk of UDLR steps with ? wildcards that can stop after any prefix, and you report the smallest and largest reachable X and Y.	Medium4	GreedySimulation	No attempts yet	1s	128 MB	Judgeable
Longest Balanced Sub-SequenceFind the length of the longest contiguous block with equal counts of positive and negative numbers.	Medium4	Prefix sumHash map	No attempts yet	1s	128 MB	Judgeable
Spiral CoordinatesFind the (row, column) of N in the clockwise integer spiral centered at 1.	Medium4	Math	No attempts yet	1s	128 MB	Judgeable
Tree ColoringCount colorings of an N-node tree with K colors so adjacent nodes differ, modulo 93563.	Medium4	Dynamic programmingTree+1	No attempts yet	1s	128 MB	Judgeable
Diamond Mining ProfitsFind the contiguous period with the largest total gain across up to 2000 test cases, breaking ties by shorter length then earlier start.	Medium4	Dynamic programmingArray+1	No attempts yet	1s	128 MB	Judgeable
Sums of Distinct Natural NumbersCount the partitions of each given N into distinct positive integers, including N itself, modulo 100999.	Medium4	Dynamic programmingCombinatorics	No attempts yet	7s	128 MB	Judgeable
Magic Multiplying MachineChoose any subset of the given levers, including none, to maximize the product of chosen numbers modulo M.	Medium4	Dynamic programmingMath	No attempts yet	2s	64 MB	Judgeable