Interview warm-up

Short whiteboard warmups

Under construction

Still being built. Things may change

Total results4,881 problems

Guess the Numbers
Medium4
Brute force, Recursion+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Slim Span
Medium4
Union-find, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Touchscreen Keyboard
Medium4
String, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Indiana Jones and the Lost Soccer Cup
Medium4
Topological sort, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Flash Mob
Medium4
Sorting, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Knitting
Medium4
Math, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Combination Lock
Medium4
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Course Scheduling
Medium4
Hash map, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
CD
Medium4
Two pointers, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Alaska
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Convex Hull
Medium4
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Unique Snowflakes
Medium4
Sliding window, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dominos 2
Medium4
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dominos
Medium4
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
The Dragon of Loowater
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pseudoprime
Medium4
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tree
Medium4
Tree, Recursion+1
No attempts yet
Time limit
1s
Memory limit
192 MB
Judgeable
Tautology
Medium4
String, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rock-Paper-Scissors Tournament
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tic Tac Toe
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Airline Hub
Medium4
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Trip
Medium4
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
CDVII
Medium4
Simulation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crypt Kicker II
Medium4
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Contest Scoreboard
Medium4
Implementation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Smart Brain is a Tasty Brain
Medium4
String, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Let the Wookiee Win!
Medium4
Implementation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The History of the Sith Rulers
Medium4
Sorting, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
PropBot
Medium4
Brute force, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
This Is Halloween: Saving Money
Medium4
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tribute (Editor)
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Repeated Rounding
Medium4
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Relative Relatives
Medium4
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Electronic Document Security
Medium4
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Root
Medium4
Binary search, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pascal's Travels
Medium4
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jungle Roads
Medium4
Minimum spanning tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Image Perimeters
Medium4
BFS, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Instruens Fabulam
Medium4
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Myacm Triangles
Medium4
Brute force, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Automatic Editing
Medium4
String, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robot Motion
Medium4
Simulation, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Oil Deposits
Medium4
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mapmaker
Medium4
Array, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Equation Elation
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
DNA Translation
Medium4
String, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Underground Cables
Medium4
Minimum spanning tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bulls and Cows
Medium4
Brute force, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shrew-ology
Medium4
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Portfolio Rebalancing
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tree Grafting
Medium4
Tree, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Baskets of Gold Coins
Medium4
Math, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shortest Prefixes
Medium4
Trie, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Musical Chairs
Medium4
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Wooden Blocks
Medium4
Implementation, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Still Johnny Can't Add
Medium4
Array, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pablo Squarson's Headache
Medium4
Simulation, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Amazing Mazes
Medium4
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Next Mayor
Medium4
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Elevator
Medium4
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Phone List
Medium4
Trie, String+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Web Pages
Medium4
Stack, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maps
Medium4
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Matrix Powers
Medium4
Matrix, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Preventing Paradoxes
Medium4
Geometry, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Exotic Foods
Medium4
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Oily Currents
Medium4
Simulation, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Who Is the Winner?
Medium4
Implementation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pythagorean Triples
Medium4
Hash map, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shut the Box I
Medium4
Backtracking, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Most Frequent Square
Medium4
Brute force, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prefix Codes
Medium4
Tree, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Factoring
Medium4
Number theory, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Transport
Medium4
Brute force, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coin Collection
Medium4
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Open Intervals
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quick out of the Harbour
Medium4
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Diamond Dealer
Medium4
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
AC
Medium4
Implementation, Array+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Parking Lot
Medium4
Simulation, Queue+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Signboard
Medium4
String, Brute force+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
The Best Pizza
Medium4
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pasta
Medium4
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Planet Exploration
Medium4
Prefix sum, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cheese
Medium4
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Wedding
Medium4
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Longest Staircase
Medium4
Sorting, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Product Order Totals
Medium4
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tornado!
Medium4
Greedy, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hour Hand and Minute Hand
Medium4
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
King's Poker
Medium4
Implementation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Average and Median
Medium4
Math, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hexagonal Tiles
Medium4
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Brothers
Medium4
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Soccer League
Medium4
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dice
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Noise Effect
Medium4
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Avoiding a Disaster
Medium4
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Crossings
Medium4
Sorting, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Perimeter
Medium4
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Guess the NumbersDetermine whether some permutation of up to 5 given values assigned to the unknowns in a fully parenthesized arithmetic expression makes it evaluate to a target result.	Medium4	Brute forceRecursion+1	No attempts yet	1s	128 MB	Judgeable
Slim SpanGiven a weighted graph, find the spanning tree that minimizes the difference between its largest and smallest edge weight, or report -1 if disconnected.	Medium4	Union-findSorting+1	No attempts yet	2s	128 MB	Judgeable
Touchscreen KeyboardGiven a typed word and a list of same-length dictionary words, print each with its keyboard Manhattan distance, sorted by distance then lexicographically.	Medium4	StringSorting+2	No attempts yet	1s	128 MB	Judgeable
Indiana Jones and the Lost Soccer CupGiven precedence constraints between levers, decide whether the order is unique; print the unique order, or report no order or multiple orders.	Medium4	Topological sortGraph+2	No attempts yet	1s	256 MB	Judgeable
Flash MobGiven n grid points, find the intersection minimizing the total Manhattan distance, breaking ties by smallest x then smallest y.	Medium4	SortingMath+2	No attempts yet	1s	128 MB	Judgeable
KnittingGiven a starting stitch count, a row total, and a repeating pattern of row change values, compute the sum of all row stitch counts for each project until the 0 0 0 terminator.	Medium4	MathPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Combination LockFor each lock, find the largest total number of ticks turned over the three stages, maximized over all possible starting positions of the dial.	Medium4	MathSimulation+1	No attempts yet	1s	128 MB	Judgeable
Course SchedulingGiven n course requests as (first name, last name, course) triples, count the distinct students per course and print courses in ASCII order.	Medium4	Hash mapSorting	No attempts yet	1s	128 MB	Judgeable
CDGiven two sorted lists of distinct CD numbers, count how many numbers appear in both lists.	Medium4	Two pointersSorting+1	No attempts yet	1s	256 MB	Judgeable
AlaskaGiven charging station positions along a 1422-mile highway and a 200-mile range, decide whether the round trip Dawson Creek to Delta Junction and back is possible.	Medium4	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Convex HullGiven points already labeled as hull or non-hull, output only the hull points in counterclockwise order starting from the lexicographically smallest one.	Medium4	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Unique SnowflakesGiven a stream of integer snowflake ids, find the length of the longest contiguous block in which every value is distinct.	Medium4	Sliding windowHash map+2	No attempts yet	1s	128 MB	Judgeable
Dominos 2Given directed edges between dominos and a set of manually pushed dominos, count how many dominos end up falling.	Medium4	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
DominosGiven a directed graph of domino toppling relations, find the minimum number of blocks to push by hand so that all blocks fall.	Medium4	GraphDFS+1	No attempts yet	1s	256 MB	Judgeable
The Dragon of LoowaterMatch the smallest knight to each dragon head so that every head is cut by a tall enough knight, minimizing total height paid; report failure if impossible.	Medium4	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
PseudoprimeFor each pair p and a, decide whether p is composite and satisfies a^p mod p == a, printing yes or no.	Medium4	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
TreeGiven the preorder and inorder traversals of a binary tree, reconstruct the tree and print its postorder traversal.	Medium4	TreeRecursion+1	No attempts yet	1s	192 MB	Judgeable
TautologyGiven propositional formulas in Polish notation, decide for each whether it is a tautology by parsing and evaluating it over every truth assignment.	Medium4	StringRecursion+2	No attempts yet	1s	128 MB	Judgeable
Rock-Paper-Scissors TournamentCount wins and losses for each player across all games, then print each player's win average w/(w+l) to three decimals, or - if the denominator is 0.	Medium4	SimulationImplementation+2	No attempts yet	1s	256 MB	Judgeable
Tic Tac ToeGiven a 3x3 Tic Tac Toe grid, decide whether some legal sequence of moves could produce exactly that position.	Medium4	ImplementationSimulation+2	No attempts yet	1s	128 MB	Judgeable
Airline HubGiven up to 1000 airports by latitude and longitude, pick the one minimizing the largest great-circle distance to any other airport, breaking ties by earliest input order.	Medium4	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
The TripGiven what each student spent, find the minimum total money that must change hands so every student ends up paying the same amount within one cent.	Medium4	GreedyMath+2	No attempts yet	1s	128 MB	Judgeable
CDVIIPair each vehicle's enter records with the immediately following exit, charge per-kilometre tolls by start hour plus fees, and print sorted totals in dollars.	Medium4	SimulationSorting+2	No attempts yet	1s	128 MB	Judgeable
Crypt Kicker IIOne input line is the pangram 'the quick brown fox jumps over the lazy dog' encrypted by a letter substitution; find it, build the table, and decrypt every line.	Medium4	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Contest ScoreboardGiven judging queue entries, compute each contestant's solved count and penalty time, then print the standings in rank order.	Medium4	ImplementationSorting+2	No attempts yet	1s	128 MB	Judgeable
A Smart Brain is a Tasty BrainParse each of up to 10000 Boolean expressions, evaluate it, and report whether the brain's given answer matches.	Medium4	StringStack+2	No attempts yet	1s	128 MB	Judgeable
Let the Wookiee Win!On a 5x5 board, find the single empty square where playing O neither makes four O in a row nor blocks any of X's winning squares.	Medium4	ImplementationBrute force+2	No attempts yet	1s	128 MB	Judgeable
The History of the Sith RulersGiven up to 50 rulers with the start and end months of each reign, report which rulers held power during each queried year, in order.	Medium4	SortingImplementation+2	No attempts yet	1s	128 MB	Judgeable
PropBotGiven at most 24 seconds, each spent moving 10 cm forward or turning 45 degrees right, find the closest reachable point to a target and print its distance to six decimals.	Medium4	Brute forceGeometry+2	No attempts yet	1s	128 MB	Judgeable
This Is Halloween: Saving MoneyFor each box, compute the exact wrapping paper area from its dimensions and truncate the result to a given number of significant digits.	Medium4	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Tribute (Editor)Simulate a buggy modal editor: given keystrokes, apply insert, delete, duplicate, reverse, and cursor commands, then print the buffer with a caret marking the cursor position.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Repeated RoundingRound each integer repeatedly at increasing place values (ones, tens, hundreds, ...) using round-half-up until the value no longer exceeds the current threshold.	Medium4	MathImplementation+1	No attempts yet	1s	128 MB	Judgeable
Relative RelativesGiven Ted's age of 100 and each descendant's father name plus the father's age at the child's birth, compute every descendant's age and list them oldest first, ties broken by name.	Medium4	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Electronic Document SecurityProcess a log of ACL +, -, = entries in order and print the final rights for each entity, merging entities with identical rights.	Medium4	ImplementationSimulation+2	No attempts yet	1s	128 MB	Judgeable
RootFor each pair B and N, find the positive integer A that makes A^N as close to B as possible.	Medium4	Binary searchMath+2	No attempts yet	1s	128 MB	Judgeable
Pascal's TravelsCount paths on an n by n digit board from top-left to bottom-right, where each square's digit sets the exact right or down step length.	Medium4	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Jungle RoadsGiven a connected weighted graph of villages and roads, find the minimum total maintenance cost of a set of roads that keeps every village connected.	Medium4	Minimum spanning treeGraph+2	No attempts yet	1s	128 MB	Judgeable
Image PerimetersGiven a grid and a click, find all X squares connected to the click by 8-direction adjacency and report the perimeter of that object.	Medium4	BFSDFS+2	No attempts yet	1s	128 MB	Judgeable
Instruens FabulamRead a header specifying each column's alignment, then print each table with borders, sized columns, and aligned cells.	Medium4	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
Myacm TrianglesAmong 4 to 15 labeled points, find the triangle with the largest area that contains no other point inside or on its edges.	Medium4	Brute forceGeometry+2	No attempts yet	1s	128 MB	Judgeable
Automatic EditingApply a fixed list of find-and-replace rules in order, repeatedly replacing the first occurrence of each find string until it no longer appears, and print the final text.	Medium4	StringSimulation+2	No attempts yet	1s	128 MB	Judgeable
Robot MotionSimulate a robot walking a grid of N/S/E/W arrows from a given top column, and report either the steps to exit or the steps before a loop plus its length.	Medium4	SimulationGraph+1	No attempts yet	1s	128 MB	Judgeable
Oil DepositsCount connected components of oil pockets (@) in a grid where cells connect in all eight directions; input ends when m is 0.	Medium4	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
MapmakerGiven array declarations with bounds and element sizes, compute each reference's physical address with the row-major address formula.	Medium4	ArrayMath+2	No attempts yet	1s	128 MB	Judgeable
Equation ElationRepeatedly reduce an arithmetic expression on the left of an equals sign by performing one operation at a time in precedence order, printing each intermediate line.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
DNA TranslationFor each DNA strand, try all four readings (forward, reverse, complement, reverse complement), translate the first AUG to the first stop codon, and print the lexicographically greatest valid protein or a failure message.	Medium4	StringSimulation+2	No attempts yet	1s	128 MB	Judgeable
Underground CablesGiven up to 1000 points, connect them all with straight line segments of minimum total length, with no two segments crossing.	Medium4	Minimum spanning treeGraph+2	No attempts yet	1s	128 MB	Judgeable
Bulls and CowsGiven a transcript of Bulls and Cows guesses and replies for codes of length up to 7 with distinct digits, count the codes consistent with all replies and print the smallest one.	Medium4	Brute forceImplementation	No attempts yet	1s	128 MB	Judgeable
Shrew-ologyGiven per-trait dominance rules and adult shrews with sex and trait bits, list every mother-father pair that could produce each juvenile.	Medium4	Brute forceImplementation+2	No attempts yet	1s	128 MB	Judgeable
Portfolio RebalancingSimulate each term's fixed fee, percentage fee, and return per instrument, pool and redistribute every NREBALANCE terms, and print each ending balance to two decimals.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Tree GraftingGiven a depth-first traversal string of an ordered tree, report its height and the height after converting it to a left-child/right-sibling binary tree.	Medium4	TreeStack+2	No attempts yet	1s	128 MB	Judgeable
Baskets of Gold CoinsGiven the total weight of coins drawn with counts 1..N-1 from N baskets, find which basket holds the lighter coins.	Medium4	MathBrute force+2	No attempts yet	1s	128 MB	Judgeable
Shortest PrefixesFor each word in a list, find the shortest prefix that matches only that word, counting an exact match as unique even if longer words share it.	Medium4	TrieString+2	No attempts yet	1s	128 MB	Judgeable
Musical ChairsGiven N children in a circle and a step D, repeatedly remove the D-th child counting around the circle; report the last child left plus N and D.	Medium4	MathSimulation+2	No attempts yet	1s	128 MB	Judgeable
Wooden BlocksGiven a string of digit pieces, check whether it forms a valid interlocking arrangement starting with piece 1, ending with piece 2, and matching every adjacent edge pair.	Medium4	ImplementationString+2	No attempts yet	1s	128 MB	Judgeable
Still Johnny Can't AddDecide whether an N by N grid can be written as row label plus column label for all cells, up to N=10.	Medium4	ArrayMath+2	No attempts yet	1s	128 MB	Judgeable
Pablo Squarson's HeadacheGiven how N unit squares are attached one by one to an existing square in one of four directions, compute the width and height of the resulting figure.	Medium4	SimulationArray+2	No attempts yet	1s	128 MB	Judgeable
Amazing MazesGiven a rectangular grid with walls between cells, find the number of cells on the shortest path from the top-left opening to the bottom-right opening, or 0 if none exists.	Medium4	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Next MayorSimulate the pebble-passing game and output the index of the candidate who ends up holding every pebble.	Medium4	SimulationImplementation	No attempts yet	1s	128 MB	Judgeable
ElevatorAn elevator with buttons that move up U or down D floors, staying within floors 1 to F, needs the minimum presses to go from floor S to floor G.	Medium4	BFSGraph+2	No attempts yet	1s	256 MB	Judgeable
Phone ListGiven a list of distinct phone numbers, decide whether any number is a prefix of another.	Medium4	TrieString+1	No attempts yet	1s	256 MB	Judgeable
Web PagesFor each line of HTML-looking text, decide whether every opening tag has a matching closing tag and all tags nest properly.	Medium4	StackString+2	No attempts yet	1s	128 MB	Judgeable
MapsFor each scenario, count how many positions in the map contain an exact, non-rotated copy of the rig pattern, with both X and dot cells matching. The image is trimmed, so every position in its bounding box matters.	Medium4	Brute forceImplementation+2	No attempts yet	1s	128 MB	Judgeable
Matrix PowersGiven a square matrix, a modulus, and an exponent, compute the matrix raised to that power with all entries kept modulo M.	Medium4	MatrixDivide and conquer+1	No attempts yet	1s	128 MB	Judgeable
Preventing ParadoxesGiven the vertices of a simple polygon in order, decide whether the traversal orientation is clockwise or counterclockwise.	Medium4	GeometryImplementation	No attempts yet	1s	128 MB	Judgeable
Exotic FoodsGiven a sequence of food values, choose a subset with no two chosen positions adjacent so the total value is as large as possible.	Medium4	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Oily CurrentsSimulate oil spreading on a grid for t steps, where each contaminated cell pushes oil up to its strength in its current's direction. Print the final contaminated cells.	Medium4	SimulationBFS+2	No attempts yet	1s	128 MB	Judgeable
Who Is the Winner?Given a log of contest submissions with verdicts and times, compute each contestant's solved count and ICPC-style penalty score, then output them ranked.	Medium4	ImplementationSorting+2	No attempts yet	1s	128 MB	Judgeable
Pythagorean TriplesGiven up to 50 distinct positive integers, list all Pythagorean triples x<y<z present in the set, sorted lexicographically, or report that none exist.	Medium4	Hash mapMath+2	No attempts yet	1s	128 MB	Judgeable
Shut the Box IGiven a target sum and a sorted list of open card values, choose the subset summing to the target that is lexicographically largest when sorted.	Medium4	BacktrackingArray+2	No attempts yet	1s	128 MB	Judgeable
Most Frequent SquareGiven up to 30 integer grid points, count all axis-parallel squares formed by four of them and report the side length with the most squares, breaking ties by the largest length.	Medium4	Brute forceGeometry+2	No attempts yet	1s	128 MB	Judgeable
Prefix CodesDecode several binary messages with a prefix code given as a heap-indexed tree string, where a bit 0 or 1 walks to a child until a leaf symbol is reached.	Medium4	TreeImplementation+2	No attempts yet	1s	128 MB	Judgeable
FactoringFor each integer, print 'prime' or its prime factorization in ascending order with repeated factors listed.	Medium4	Number theoryImplementation	No attempts yet	1s	128 MB	Judgeable
TransportWith at most 20 items, choose a subset whose total weight is at most W and whose total value is as large as possible.	Medium4	Brute forceBacktracking+1	No attempts yet	1s	128 MB	Judgeable
Coin CollectionA robot walks right or down only from the top-left to the bottom-right of a grid, and we want the most coins it can pick up along the way.	Medium4	Dynamic programmingMatrix+2	No attempts yet	1s	128 MB	Judgeable
Open IntervalsGiven up to 50 open intervals per test case, pick the largest subset where no two intervals overlap, counting touching endpoints as compatible.	Medium4	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Quick out of the HarbourFind the shortest time from S to outside the grid, where water cells cost 1 and drawbridges cost 1+d, on a grid up to 500x500.	Medium4	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Diamond DealerFor each simple polygon given clockwise, count concave vertices (dents) and edges not touching any dent, then print max(-ap + bq, 0).	Medium4	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
ACApply a string of reverse (R) and discard-first (D) operations to an integer array, printing the result or error if D hits an empty array.	Medium4	ImplementationArray+1	No attempts yet	1s	256 MB	Judgeable
Parking LotSimulate cars arriving and leaving a parking lot, assigning each to the lowest-numbered free space or a waiting queue, and sum weight times rate.	Medium4	SimulationQueue+2	No attempts yet	1s	128 MB	Judgeable
SignboardCount how many of the given strings contain the store name as an equally spaced subsequence, where each string counts at most once.	Medium4	StringBrute force+1	No attempts yet	1s	256 MB	Judgeable
The Best PizzaChoose any subset of toppings, each costing B, to maximize total calories divided by total price, and print the floor of that ratio.	Medium4	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
PastaCount sequences of length N over three kinds where no kind appears three or more times in a row, with some positions fixed, modulo 10000.	Medium4	Dynamic programmingImplementation	No attempts yet	1s	128 MB	Judgeable
Planet ExplorationGiven a grid of jungle, sea, and ice cells, answer many rectangle queries by counting how many cells of each terrain type fall inside.	Medium4	Prefix sumArray+2	No attempts yet	1s	256 MB	Judgeable
CheeseIn a grid maze, find the total shortest walking time for a mouse to eat cheeses of hardness 1 through N in order, each raising its strength by one.	Medium4	BFSGraph+2	No attempts yet	1s	256 MB	Judgeable
WeddingGiven a friendship graph among n classmates, count everyone within distance 2 of classmate 1.	Medium4	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
The Longest StaircaseGiven k cards with distinct values 1 to n plus one blank card (0) you can set to any value, find the longest run of consecutive integers formable.	Medium4	SortingTwo pointers+1	No attempts yet	1s	128 MB	Judgeable
Product Order TotalsSum the order quantities for each distinct product name, then print each product with its total sorted by name length, then alphabetically.	Medium4	Hash mapSorting+2	No attempts yet	1s	128 MB	Judgeable
Tornado!Given a circular fence of N posts marked standing or broken, choose the fewest broken posts to fill so no wire span between standing posts exceeds 4 meters.	Medium4	GreedyArray+2	No attempts yet	1s	128 MB	Judgeable
Hour Hand and Minute HandGiven an integer A, decide whether the hour and minute hands of a ticking clock can ever form an angle of exactly A degrees. Read A until EOF.	Medium4	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
King's PokerGiven a three-card poker hand, print the weakest set or pair that beats it, or * if none exists.	Medium4	ImplementationSorting+2	No attempts yet	1s	128 MB	Judgeable
Average and MedianFor each pair A and B, find the smallest integer C so that the average and the median of A, B, C are equal.	Medium4	MathSorting+2	No attempts yet	1s	128 MB	Judgeable
Hexagonal TilesCount the sequences of increasing tile numbers from the start tile to tile N, where each move goes forward by 1 or 2.	Medium4	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
BrothersGiven a grid of counties owned by heirs in a cycle, apply K simultaneous rounds where a cell switches to the previous heir if an orthogonal neighbor already has that heir, then print the grid.	Medium4	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Soccer LeagueRead a list of soccer match results and output the league table sorted by points, then goal difference, then first appearance in the input.	Medium4	Hash mapSorting+2	No attempts yet	1s	128 MB	Judgeable
DiceSimulate a board game where players advance by dice totals, skip a turn when landing on one of three traps, and the first past the last square wins.	Medium4	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Noise EffectGiven two L by L grayscale images, find the highest percentage of scanned pixels whose value differs from the corresponding standard pixel by at most 100 over the eight rotations and flips.	Medium4	ImplementationMath+1	No attempts yet	1s	128 MB	Judgeable
Avoiding a DisasterThree 12-hour watch readings come from one correct time, one watch x minutes slow, and one x minutes fast, with x at most 480; find the unique correct time or report ambiguity.	Medium4	Brute forceImplementation+2	No attempts yet	1s	128 MB	Judgeable
Cow CrossingsCount cows whose straight crossing paths intersect no other cow, where two paths cross exactly when the start and end left-to-right orders differ.	Medium4	SortingArray+2	No attempts yet	1s	128 MB	Judgeable
PerimeterGiven up to 10000 occupied cells in a 100 by 100 grid forming one connected region, find the outer perimeter, ignoring any holes.	Medium4	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable