Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,617 problems

Absurd Prices
Medium6
Math, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hacking
Medium6
String, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Convention Center
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Town Square
Medium6
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mobile
Medium6
Tree, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Flood
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Puzzling Problem
Medium6
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pizza Delivery Minimum Time
Medium6
Shortest path, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Data Recovery
Medium6
Graph, Prefix sum+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Roller Coaster
Medium6
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robot Challenge
Medium6
Dynamic programming, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Compound Words
Medium6
Trie, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fire!
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cranes
Medium6
Brute force, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
WiFi
Medium6
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Friend Network
Medium6
Union-find, Hash map+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Train Sorting
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balance
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tournament
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Security Company
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Translations
Medium6
Graph, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Water Main Break, Fixed
Medium6
Brute force, Greedy+2
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Pushing Boxes
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Trip (2007)
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Walk Through the Forest
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ultra-QuickSort
Medium6
Divide and conquer, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Work Reduction
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Euclid's Game
Medium6
Game theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Build a Square from Sticks
Medium6
Backtracking, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Star, Not a Tree?
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Adventures in Moving - Part IV
Medium6
Greedy, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pairsumonious Numbers
Medium6
Sorting, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
No Tipping
Medium6
Backtracking, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gopher II
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bridge Crossing
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dick and Jane
Medium6
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
I'm Attacking the Darkness!
Medium6
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Children of the Candy Corn
Medium6
BFS, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Any Way You Slice It
Medium6
Geometry, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bulletin Board
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Go Go Gorelians
Medium6
Graph, Tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robots
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Falling Leaves
Medium6
Tree, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Exchange Rates
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Don't Get Rooked
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Puzzling Problem
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Roller Coaster
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Extended Manhattan Distance
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stringer
Medium6
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Context-Free Clock
Medium6
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chemistry
Medium6
Stack, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Removing Parentheses
Medium6
Stack, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Resistors
Medium6
String, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Last Digits
Medium6
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Newton's Apple
Medium6
Tree, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cliff Climbing
Medium6
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Curling 2.0
Medium6
DFS, Backtracking+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
The Genome Database of All Space Life
Medium6
String, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Finding a Multiple
Medium6
BFS, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bread Sorting
Medium6
Array, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Doorman
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Juice
Medium6
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Complaint Sort
Medium6
Array, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Chemical Analysis
Medium6
Bit manipulation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Zebra Herd
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
7s
Memory limit
128 MB
Judgeable
Essay Writing
Medium6
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Warehouse Location Planning
Medium6
Brute force, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Computer Science
Medium6
Implementation, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Butterfly Ballots
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Volleyball Scores
Medium6
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rotation Maze
Medium6
BFS, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Valid Binary String
Medium6
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Buying Notebooks
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fractal Distance
Medium6
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Warfare
Medium6
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cell Phone Antenna
Medium6
Geometry, Intervals+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Digit Sum of a Range
Medium6
Math, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fire!
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Equal Is Not Really Equal
Medium6
Graph, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Raisins
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Palindrome
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Party Lamps
Medium6
Brute force, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Darts
Medium6
Binary search, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Light Bulb Decoration
Medium6
Array, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Used Bookstore
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shopping Malls
Medium6
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Microbe Experiment (Bug Party)
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
First Grade
Medium6
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Splitting the Snack
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hop-Hop River Crossing
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Senbei
Medium6
Brute force, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sea Journey
Medium6
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Oldest Ruins
Medium6
Geometry, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Worst Reporter
Medium6
Graph, Topological sort+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Third Smallest Number
Medium6
String, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bacteria
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Binary Search Tree
Medium6
Tree, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
App Rating
Medium6
Math, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stacking Balls
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dinner Hall
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Absurd PricesGiven a price in cents, decide whether some integer within 5 percent (rounded to a closed interval) has strictly smaller digit-based absurdity, where absurdity is twice the digit count minus one if the last nonzero digit is 5.	Medium6	MathBrute force+2	No attempts yet	1s	128 MB	Judgeable
HackingFind the shortest lexicographically smallest string over the first k letters that appears nowhere as a substring of a given text, with length capped at m.	Medium6	StringBinary search+2	No attempts yet	1s	512 MB	Judgeable
Convention CenterChoose the largest set of non-overlapping day intervals, breaking ties by picking the set of group indices that is lexicographically smallest.	Medium6	GreedySorting+2	No attempts yet	2s	64 MB	Judgeable
Town SquareGiven four statue points, find the side length of the largest square whose four sides each sit exactly 5 feet from one distinct statue.	Medium6	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
MobileGiven a mobile's arm structure and pivot distances, find the smallest integer weights, with a named weight at least w, that keep every arm balanced.	Medium6	TreeMath+2	No attempts yet	1s	128 MB	Judgeable
The FloodGiven a grid of altitudes, find the lowest water level at which the dry land splits into two or more connected pieces, where water floods inward from outside.	Medium6	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
A Puzzling ProblemGiven a word search grid and word list, decide whether removing any single word ever disconnects the remaining words from one another.	Medium6	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Pizza Delivery Minimum TimeGiven directed travel times between a pizzeria and up to 10 stops, find the shortest round trip from the pizzeria visiting every stop.	Medium6	Shortest pathDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Data RecoveryGiven a grid with some unknown cells plus all row and column sums, print each unknown cell's forced value, or -1 if several values fit.	Medium6	GraphPrefix sum+2	No attempts yet	5s	128 MB	Judgeable
Roller CoasterEach section of a roller coaster either adds fun and dizziness or reduces dizziness by K; find the maximum fun keeping dizziness at or below L at all times.	Medium6	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
Robot ChallengeThe robot starts at (0,0), must visit targets in order, and may skip any target by paying its penalty. Find the minimum total time plus penalties to reach (100,100).	Medium6	Dynamic programmingGeometry+2	No attempts yet	1s	128 MB	Judgeable
Compound WordsGiven a dictionary of up to 120,000 sorted lowercase words, list every word that can be split into two shorter dictionary words.	Medium6	TrieString+2	No attempts yet	1s	128 MB	Judgeable
Fire!Given a grid with walls, one starting cell, and burning cells, find the earliest minute Jihoon can step off the edge, given the fire spreads one cell per minute.	Medium6	BFSGraph+2	No attempts yet	1s	256 MB	Judgeable
CranesChoose a subset of at most 15 crane locations, each with a radius, so that every pair's distance exceeds the sum of radii, maximizing the total squared radius.	Medium6	Brute forceGeometry+2	No attempts yet	1s	128 MB	Judgeable
WiFiGiven house positions on a line and a budget of n access points, place them to minimize the maximum distance from any house to its nearest access point.	Medium6	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
Friend NetworkProcess friendships one by one and after each union print the size of the merged friend network containing the two users.	Medium6	Union-findHash map+1	No attempts yet	3s	256 MB	Judgeable
Train SortingCars arrive in a fixed order; each can be attached to the front, the back, or skipped, keeping weights strictly decreasing front to back. Find the longest train.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
BalanceGiven the polygon outline of a boat's side view, compute the centroid above and below the waterline and report whether the Center of Effort is forward, aft, or balanced, with the difference rounded to two decimals.	Medium6	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
TournamentGiven k knights with abilities, choose 2^e - k of them to sit out the first round and pair the rest to minimize the sum of squared ability differences.	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Security CompanyPoints lie on a line with travel times between neighbors; starting from point a and visiting every point, minimize the total first-arrival time over all points.	Medium6	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
TranslationsGiven two alphabetically sorted lists of two-word phrases in two languages, reconstruct the unknown one-to-one word translation mapping. Print each source word with its translation, sorted.	Medium6	GraphHash map+2	No attempts yet	1s	128 MB	Judgeable
Water Main Break, FixedA crew starts at the origin and must visit up to 10 breaks in some order; pick the order that minimizes total water lost, where each break waits until its start time.	Medium6	Brute forceGreedy+2	No attempts yet	8s	128 MB	Judgeable
Pushing BoxesSimulate pushes of the four walls on unit boxes, stopping each wall when boxes are packed against the opposite wall, and report final positions sorted top-to-bottom, left-to-right.	Medium6	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
The Trip (2007)Given n bag sizes where a strictly smaller bag fits inside a larger one, find the minimum number of outermost pieces and then the smallest possible size of the largest nested piece.	Medium6	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
A Walk Through the ForestCount the number of routes from intersection 1 to 2 in an undirected weighted graph where each step strictly decreases the shortest distance to intersection 2.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Ultra-QuickSortGiven a sequence of distinct integers, count the minimum number of adjacent swaps needed to sort it, which is the number of inversions.	Medium6	Divide and conquerSorting+2	No attempts yet	1s	256 MB	Judgeable
Work ReductionFor each agency with per-unit cost A and halving cost B, find the minimum cost to cut N units of paperwork down to exactly M.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Euclid's GameGiven two starting numbers, decide who wins the subtraction game Euclid's Game under optimal play, for each pair until the terminating 0 0 line.	Medium6	Game theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Build a Square from SticksGiven up to 20 stick lengths, decide whether all sticks can be split into four groups of equal total length.	Medium6	BacktrackingRecursion+2	No attempts yet	1s	128 MB	Judgeable
A Star, Not a Tree?Given up to 100 points in the plane, pick one hub location that minimizes the sum of Euclidean distances to all points, and report the rounded minimum.	Medium6	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Adventures in Moving - Part IVGiven a route with up to 100 gas stations, each with a price per litre, find the cheapest way to fuel a truck with a 200-litre tank that starts and ends half full.	Medium6	GreedyDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Pairsumonious NumbersGiven all pairwise sums of N numbers, recover the N numbers in non-descending order, choosing the lexicographically smallest set or reporting Impossible.	Medium6	SortingMath+2	No attempts yet	1s	128 MB	Judgeable
No TippingCount the orders in which n packages can be removed from a lever on two fulcrums so the board never tips.	Medium6	BacktrackingBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
Gopher IIEach gopher escapes if some hole within s*v metres is assigned to it, one gopher per hole; minimize the number of gophers left out by finding a maximum matching.	Medium6	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
Bridge CrossingGiven n people's crossing times and one flashlight, find the minimum total time to move everyone across when at most two cross together.	Medium6	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Dick and JaneGiven that Spot was s when Puff was born, Puff was p when Yertle was born, and Spot was y when Yertle was born, find the three current ages.	Medium6	MathBrute force+1	No attempts yet	1s	128 MB	Judgeable
I'm Attacking the Darkness!Parse a dice expression with up to six dice and integer modifiers, then compute the reduced fraction of outcomes whose total meets or beats a target value.	Medium6	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
Children of the Candy CornFor each maze, report the number of squares visited along the left-hand wall-following route, the right-hand route, and the shortest route from S to E.	Medium6	BFSSimulation+2	No attempts yet	1s	128 MB	Judgeable
Any Way You Slice ItSimulate a laser cutter's path from turn and move instructions and report the first move that crosses an earlier cut segment, forming a hole.	Medium6	GeometrySimulation+2	No attempts yet	1s	128 MB	Judgeable
Bulletin BoardGiven up to 100 axis-aligned rectangles on a board, report the uncovered area, the maximum overlap depth, and the area covered at exactly that depth.	Medium6	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Go Go GoreliansBuild the network by linking each new planet to the nearest existing planet, then find the planet or two adjacent planets that minimize the maximum distance to all others.	Medium6	GraphTree+2	No attempts yet	1s	128 MB	Judgeable
RobotsGiven garbage cells in a grid, robots walk from the northwest corner to the southeast corner moving only east or south; find the fewest robots that collect all garbage.	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Falling LeavesGiven the leaf-removal stages of a binary search tree, reconstruct the unique tree and print its preorder traversal.	Medium6	TreeRecursion+2	No attempts yet	1s	128 MB	Judgeable
Exchange RatesMaintain exchange rates between named items as assertions arrive, then answer each query with the rate in lowest terms or question marks if unknown.	Medium6	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
Don't Get RookedFind the maximum number of non-attacking rooks on a board up to 4x4 where walls block rook attacks.	Medium6	BacktrackingBrute force+2	No attempts yet	1s	128 MB	Judgeable
A Puzzling ProblemPlace up to 5 fixed-orientation polyomino pieces, each labeled by index, to tile a 4x4 square exactly, printing the lexicographically smallest labeled grid or a failure message.	Medium6	BacktrackingBrute force+2	No attempts yet	1s	128 MB	Judgeable
Roller CoasterChoose open or closed eyes for each roller coaster section to maximize total fun while keeping dizziness within limit L, where closing decreases dizziness by K.	Medium6	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Extended Manhattan DistanceGiven an axis-aligned city grid and two integer points, find the shortest path length when travel inside the grid is restricted to axis-parallel streets and travel outside is free in any direction.	Medium6	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
StringerGiven fixed counts of each of N letters, find the K-th string in alphabetical order among all arrangements, without listing them.	Medium6	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
Context-Free ClockGiven a measured clockwise angle and a start time, find the earliest time at or after it when the hour and minute hands form that angle, rounded down to the second.	Medium6	MathSimulation+2	No attempts yet	1s	128 MB	Judgeable
ChemistryParse a chemical formula with nested parentheses and multipliers, then output each element's total atom count in lexicographic order.	Medium6	StackString+2	No attempts yet	1s	128 MB	Judgeable
Removing ParenthesesGiven an expression of single-letter variables with addition and multiplication, remove every pair of parentheses that can go without changing the value, and print the result.	Medium6	StackString+2	No attempts yet	1s	128 MB	Judgeable
ResistorsParse a nested expression of series and parallel resistor connections and output the exact resistance as a reduced fraction.	Medium6	StringStack+2	No attempts yet	1s	128 MB	Judgeable
Last DigitsFor each test case, print the last n digits (with leading zeros) of the power tower of height i with base b.	Medium6	Number theoryMath+2	No attempts yet	2s	128 MB	Judgeable
Newton's AppleParse two binary trees from post-order tokens with nil markers, then decide whether one can be turned into the other by swapping left and right children at any nodes.	Medium6	TreeRecursion+2	No attempts yet	1s	128 MB	Judgeable
Cliff ClimbingFind the minimum total time for Jack to climb a grid, moving feet alternately under distance constraints, from a bottom S block to a top T block.	Medium6	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
Curling 2.0On a grid with destructible blocks, find the fewest throws to slide a curling stone from start to goal, where each slide continues until it hits a block or leaves the board.	Medium6	DFSBacktracking+2	No attempts yet	3s	128 MB	Judgeable
The Genome Database of All Space LifeDecode a run-length compressed genome string with nested parentheses and print the character at index i, or 0 if the index is out of range.	Medium6	StringRecursion+2	No attempts yet	1s	128 MB	Judgeable
Finding a MultipleFor each n up to 200, print the smallest multiple of n whose decimal digits are only 0 and 1, with up to 100 digits.	Medium6	BFSNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Bread SortingDecide whether one permutation of 1..n can be turned into another using only the operation that rotates any three adjacent elements right by one.	Medium6	ArrayGreedy+2	No attempts yet	1s	128 MB	Judgeable
DoormanGiven a queue of men and women and a limit X, repeatedly admit the front or second person so the running gender difference never exceeds X, and maximize the number admitted.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
JuiceGiven a rooted tree with cord capacities and house demands, choose which houses to power so that flow through each cord stays within capacity and the count is maximized.	Medium6	TreeDFS+2	No attempts yet	2s	128 MB	Judgeable
Complaint SortGiven a sequence of n values, count the strictly decreasing subsequence triples (i < j < k with a_i > a_j > a_k).	Medium6	ArrayCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Chemical AnalysisGiven up to 12 element bitmasks and a target bitmask, find the fewest elements whose bitwise OR equals the target, or report that none does.	Medium6	Bit manipulationBrute force+2	No attempts yet	1s	128 MB	Judgeable
Zebra HerdAssign each of z zebras one of two colors at each of t times, minimizing same-color distance costs, opposite-color bonuses, and color-change penalties.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	7s	128 MB	Judgeable
Essay WritingGiven a sample text, two keywords, and a target length w, decide whether a word sequence of exactly w words exists where every adjacent pair appears in the sample and both keywords occur at least once.	Medium6	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Warehouse Location PlanningChoose any nonempty subset of up to 20 candidate warehouses and assign each of up to 100 stores to a chosen one so that building plus Euclidean shipping cost is minimum.	Medium6	Brute forceBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Computer ScienceScore each page for a query word using occurrences in the page and in linking pages weighted by word distance to the hyperlink, then print the highest scoring pages.	Medium6	ImplementationString+2	No attempts yet	1s	128 MB	Judgeable
Butterfly BallotsGiven even intended-vote counts, choose a top-to-bottom candidate order where a half-row box shift sends half of each candidate's voters to the next candidate, and decide whether candidate 1 can tie or win.	Medium6	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Volleyball ScoresGiven a sequence of ball touches, ground hits, and out of bounds calls, compute the volleyball score while checking that the correct team serves each volley.	Medium6	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Rotation MazeGiven a maze where a ball falls under gravity, find the shortest sequence of 90-degree left and right rotations that brings the ball to rest on the goal.	Medium6	BFSSimulation+2	No attempts yet	1s	128 MB	Judgeable
Valid Binary StringGiven a binary string with erased positions, decide whether the missing bits can be filled so the counts of 0 and 1 are equal and no character runs three times in a row.	Medium6	GreedyString+2	No attempts yet	1s	128 MB	Judgeable
Buying NotebooksEach store has a fixed shipping fee, a per-notebook price, and limited stock; buy exactly N notebooks across stores at minimum total cost.	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Fractal DistanceGiven the order of two houses along an n-th Hilbert curve, compute the straight-line distance between their grid positions.	Medium6	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
WarfareGiven an undirected multigraph with per-edge cost as the sum of its endpoint weights, find the minimum total cost of edges whose removal destroys every cycle.	Medium6	GraphMinimum spanning tree+2	No attempts yet	1s	128 MB	Judgeable
Cell Phone AntennaPlace one antenna of range 1000 on the line y=0 so that the total inhabitants of all covered houses is maximized, and report that maximum.	Medium6	GeometryIntervals+2	No attempts yet	1s	128 MB	Judgeable
Digit Sum of a RangeFor each query [a,b] with b up to 10^15, output the sum of all decimal digits of every integer in the range.	Medium6	MathDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Fire!Given a grid with walls, one starting cell, and fire cells that spread each second, find the earliest time the person can step off the map.	Medium6	BFSGraph+2	No attempts yet	1s	256 MB	Judgeable
Equal Is Not Really EqualGiven a string, decide whether a different string of the same length has an identical multiset of consecutive character pairs.	Medium6	GraphString+2	No attempts yet	1s	128 MB	Judgeable
RaisinsSplit an N by M chocolate bar into unit cells by straight cuts; each cut costs the raisins in the piece, and the goal is to minimize the total payment.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	3s	128 MB	Judgeable
PalindromeGiven a string, find the minimum number of characters to insert anywhere so the string becomes a palindrome.	Medium6	Dynamic programmingString+2	No attempts yet	1s	256 MB	Judgeable
Party LampsGiven N lamps all starting ON and a press count C, list every distinct final lamp configuration reachable with exactly C presses of four fixed toggle buttons and consistent with up to two ON and two OFF constraints.	Medium6	Brute forceBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
DartsWith up to four darts and N region scores, find the largest total not exceeding M, or 0 if every reachable total is over M.	Medium6	Binary searchSorting+2	No attempts yet	1s	256 MB	Judgeable
Light Bulb DecorationGiven a binary string, flip at most one contiguous range so that some contiguous alternating substring becomes as long as possible, and report that length.	Medium6	ArrayPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
The Used BookstoreChoose exactly K of N books to sell, maxing the total where selling t books of one genre adds t(t-1) extra to that genre's group.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Shopping MallsGiven a connected weighted graph with some cities holding malls, find the maximum over all points on roads of the distance to the nearest mall, then round to the nearest integer.	Medium6	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
Microbe Experiment (Bug Party)Choose the largest subset of microbes so that the average foo released by the subset does not exceed any chosen microbe's tolerance.	Medium6	GreedySorting+2	No attempts yet	2s	128 MB	Judgeable
First GradeCount the ways to place + or - between the first N-1 digits and = before the last digit so that left-to-right evaluation never leaves the range 0 to 20 and the total equals the last digit.	Medium6	Dynamic programmingArray	No attempts yet	1s	128 MB	Judgeable
Splitting the SnackChoose which of the N-1 cut points to cut so that both people get exactly N/2 pieces, minimizing the total force of the chosen cuts.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Hop-Hop River CrossingStarting from the near bank, hop across stones in n rows using normal jumps or at most m row-skipping jumps, minimizing total jump danger.	Medium6	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
SenbeiGiven a binary R x C grid with R at most 10, choose one subset of rows and one subset of columns to flip so the number of 1s is maximized.	Medium6	Brute forceGreedy+2	No attempts yet	1s	128 MB	Judgeable
Sea JourneyProcess a stream of queries where each query asks for the shortest path between two islands after a sequence of edge insertions.	Medium6	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
The Oldest RuinsGiven up to 3000 integer points, find four that form a square of the largest area and output that area, or 0 if none exist.	Medium6	GeometryHash map+2	No attempts yet	1s	128 MB	Judgeable
The Worst ReporterGiven some match results of a round-robin where higher-ranked teams always win, find the lexicographically smallest ranking and say whether it is unique.	Medium6	GraphTopological sort+2	No attempts yet	1s	128 MB	Judgeable
The Third Smallest NumberGiven n distinct natural numbers, list all two-element ordered concatenations by value and report the third smallest.	Medium6	StringSorting+2	No attempts yet	1s	128 MB	Judgeable
BacteriaSimulate K bacteria moving on a grid, each turning by a digit read from its own matrix, and report when all share the trap cell.	Medium6	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Binary Search TreeGiven the preorder traversal of a binary search tree, print its postorder traversal.	Medium6	TreeDivide and conquer+2	No attempts yet	1s	256 MB	Judgeable
App RatingGiven a rounded average rating from 1 to 5, find the minimum number of raters whose exact average rounds to that value.	Medium6	MathBrute force+2	No attempts yet	1s	128 MB	Judgeable
Stacking BallsPick balls from a triangular pile, where each ball needs both balls above it picked first, to maximize the total score; stopping early is allowed.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Dinner HallEach card gives a distinct time, either an entry, an exit, or unknown; find the largest number of people who could have been inside at one instant.	Medium6	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable