Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,617 problems

Electricity Bill
Medium6
Binary search, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Finding Seats
Medium6
Two pointers, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Report Recovery
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Long Night of Museums
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Splitting Club
Medium6
Greedy, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
This Sentence is False
Medium6
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Will Indiana Jones Get There?
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Duty Free Shop
Medium6
Greedy, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Luxury River Cruise
Medium6
Binary search, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Farm Painting
Medium6
Sorting, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Perimeter of the Hay Bales
Medium6
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Lineup
Medium6
Sliding window, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Painting the Fence
Medium6
Intervals, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Painting the Fence
Medium6
Prefix sum, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Wi-Fi Setup
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crazy Fences
Medium6
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Landscaping
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Symmetry
Medium6
Geometry, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Nearby Cows
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Moo Game
Medium6
Recursion, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Roadblock
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Umbrellas for Cows
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Above the Median
Medium6
Prefix sum, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Visiting Cows
Medium6
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chocolate Milk
Medium6
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Treasure Chest
Medium6
Dynamic programming, Game theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Trough Game
Medium6
Brute force, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mowing the Lawn
Medium6
Dynamic programming, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Claustrophobic Cows
Medium6
Geometry, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Great Cow Gathering
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mixed Up Cows
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kaing Calendar
Medium6
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Buying Hay
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Laser Communication
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bulls and Cows
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Frisbee Team
Medium6
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Work Scheduling
Medium6
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cake
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Super Paintball
Medium6
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Milking Time
Medium6
Dynamic programming, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gourmet Grazers
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cell Phone Network
Medium6
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Meteor Shower
Medium6
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
River Crossing
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building the Moat
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Round Numbers
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Roller Coaster
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Standing Long Jump
Medium6
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Face the Right Way
Medium6
Greedy, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cheapest Palindrome
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Leaking Dike
Medium6
Array, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Party at Hali-Bula
Medium6
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Island of Logic
Medium6
Brute force, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Railroad
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Game
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shuffling Patience
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Equivalent Resistance of a Resistor Network
Medium6
Graph, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Intersection
Medium6
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Alien Security
Medium6
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Trip Routing
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Annoying Painting Tool
Medium6
Greedy, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Economic Phone Calls
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Decorate the Wall
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Even a Kindergartner Could Solve This
Medium6
String, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Run Length Encoding
Medium6
String, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Largest Rectangle in a Histogram
Medium6
Stack, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Mondrian's Dream
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hike on a Graph
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
From Dusk till Dawn (or Vladimir the Vampire)
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Frogger
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ambiguous Result
Medium6
Dynamic programming, Intervals+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Arable Area
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crane
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Electricity
Medium6
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Christmas Presents
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Directed mazes
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Language for Constants
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Returning Books
Medium6
Sorting, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Parallelogram Counting
Medium6
Hash map, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Reorganization
Medium6
Greedy, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree Pruning
Medium6
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Computer Purchase Return
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Space Miner
Medium6
Geometry, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shop and Ship
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Herding
Medium6
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Candy
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Friends
Medium6
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tin Can Telephone
Medium6
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
R & J
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Domino
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Return of Space Turtle
Medium6
Simulation, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Duathlon
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Election Night
Medium6
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Extension Cords
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maple Roundup
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum of Products
Medium6
String, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mountain Passage
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
World Cup
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stepping on Tiles
Medium6
Dynamic programming, Hash map+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tree Isomorphism
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Electricity BillGiven the combined bill A of two users and the difference B of their individual bills, find the smaller user's own bill under a four-tier progressive rate.	Medium6	Binary searchMath+2	No attempts yet	1s	128 MB	Judgeable
Finding SeatsGiven an R by C grid of free and taken seats, place K people on free seats so the bounding rectangle has the smallest area.	Medium6	Two pointersBinary search+2	No attempts yet	1s	128 MB	Judgeable
Report RecoveryRebuild a space-stripped sales report by splitting each digit run into numbers, choosing the lexicographically smallest reconstruction consistent with the report's structure.	Medium6	BacktrackingBrute force+2	No attempts yet	3s	128 MB	Judgeable
Long Night of MuseumsWith at most 20 museums, viewing times, and travel times, find the largest number of distinct museums a 420-minute tour can include.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
The Splitting ClubGiven distinct ages with member counts and a ratio R, partition all age groups into the fewest contiguous sections where the max count in a section is at most R times the min count.	Medium6	GreedyTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
This Sentence is FalseEach sentence claims another sentence is true or false; decide whether a consistent assignment exists and, if so, maximize the number of true sentences.	Medium6	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Will Indiana Jones Get There?Given axis-aligned wall segments, find the smallest board length such that a path from the first wall to the second keeps every gap no larger than that length.	Medium6	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
Duty Free ShopAssign each box entirely to one of two brands so both totals stay within limits, printing the greedy canonical assignment or Impossible to distribute.	Medium6	GreedyDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Luxury River CruiseEach of N ports has a left and right outgoing river; follow a fixed direction string of length M repeated K times from port 1 and report the final port.	Medium6	Binary searchGraph+2	No attempts yet	1s	128 MB	Judgeable
Farm PaintingGiven up to 50,000 non-intersecting axis-aligned rectangles, count how many are not contained inside any other rectangle.	Medium6	SortingArray+2	No attempts yet	1s	128 MB	Judgeable
Perimeter of the Hay BalesGiven up to 50000 grid cells forming one connected region, find the outer perimeter, ignoring any enclosed holes.	Medium6	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Cow LineupGiven a sequence of N breed IDs, remove at most K distinct breed IDs so that the longest run of equal IDs in the remaining sequence is maximized.	Medium6	Sliding windowTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
Painting the FenceBessie walks along a number line and each segment she covers gains a coat of paint; find the total length covered by at least K coats.	Medium6	IntervalsSorting+2	No attempts yet	1s	128 MB	Judgeable
Painting the FenceBessie walks back and forth along a line, each pass adding a coat; find the total length covered by at least two coats.	Medium6	Prefix sumSorting+2	No attempts yet	1s	128 MB	Judgeable
Wi-Fi SetupCover all cow positions on a line with base stations, where a station covering an interval of length 2r costs A + B*r; minimize total cost.	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Crazy FencesGiven horizontal and vertical fences that meet only at endpoints and points for cows, find the largest set of cows that can reach each other without touching a fence.	Medium6	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
LandscapingEach flowerbed has a current and target dirt amount, and dirt can be bought, removed, or moved between beds at a per-unit distance cost; find the cheapest way to hit every target.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
SymmetryGiven N distinct points in the plane, count how many lines reflect the whole set onto itself.	Medium6	GeometryHash map+2	No attempts yet	1s	128 MB	Judgeable
Nearby CowsOn a tree of N fields with C(i) cows at each field, report for every field the total cows within distance K, where K is at most 20.	Medium6	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Moo GameGiven N up to 1e9, report whether the N-th character of the recursively defined Moo sequence is 'm' or 'o'.	Medium6	RecursionDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
RoadblockGiven a weighted undirected graph, double the length of one edge to maximize the increase in the shortest path from field 1 to field N.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Umbrellas for CowsGiven cow positions on a line and a price for each umbrella width, find the cheapest set of umbrellas that covers every cow, allowing overlaps.	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Above the MedianGiven N cow heights, count contiguous ranges whose defined median (the ceil(K/2)-th smallest) is at least a threshold X.	Medium6	Prefix sumBinary search+2	No attempts yet	1s	128 MB	Judgeable
Visiting CowsGiven a tree with N vertices, choose the largest set of vertices with no two adjacent, which is the maximum independent set on a tree.	Medium6	TreeDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Chocolate MilkGiven a directed tree with N-1 edges where all flow reaches one sink, list every non-source node that lies on every root-to-sink path.	Medium6	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Treasure ChestTwo players alternately take a coin from either end of a row of N coins; find the maximum total the first player can guarantee with optimal play.	Medium6	Dynamic programmingGame theory+2	No attempts yet	1s	128 MB	Judgeable
The Trough GameGiven N troughs and M queries that each count filled troughs within a listed subset, find the filled set or report impossible or non-unique.	Medium6	Brute forceBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
Mowing the LawnGiven N cows in a row with efficiencies, pick a subset that never includes more than K adjacent cows and maximize the total efficiency.	Medium6	Dynamic programmingSliding window+2	No attempts yet	1s	128 MB	Judgeable
Claustrophobic CowsGiven up to 2000 points, find the unique pair with the smallest Euclidean distance and print their ids in increasing order.	Medium6	GeometryDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
Great Cow GatheringPick a node of a weighted tree with node weights as the gathering point, and minimize the sum of cow count times distance to that node.	Medium6	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Mixed Up CowsCount permutations of N serial numbers (N at most 16) where every adjacent pair differs by more than K.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
Kaing CalendarGiven cycle lengths M and N, find the smallest k with k mod M = x and k mod N = y, the CRT problem, or report -1.	Medium6	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
Buying HayGiven N package types with unlimited supply, each weighing P_i and costing C_i, find the minimum total cost to buy at least H pounds of hay.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Laser CommunicationOn a grid with walls and two C cells, find the fewest mirrors (/ or \) needed so a laser fired from one C reaches the other.	Medium6	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Bulls and CowsCount binary sequences of length N where every pair of bulls has at least K cows between them, modulo 5000011.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Cow Frisbee TeamCount the nonempty subsets of N cows whose rating sum is divisible by F, modulo 100000000.	Medium6	Dynamic programmingMath+2	No attempts yet	1s	128 MB	Judgeable
Work SchedulingGiven jobs each taking one unit of time with a deadline and a profit, choose a subset to schedule so total profit is maximized.	Medium6	GreedyHeap+2	No attempts yet	1s	128 MB	Judgeable
CakePartition the sequence of slice lengths into consecutive blocks, bottom to top, so each block's sum is at least the one above, and maximize the number of blocks.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Super PaintballGiven up to 100000 opponent positions on an N by N grid, count cells from which a shot along its row, column, or either diagonal would pass through every opponent.	Medium6	Brute forceImplementation+2	No attempts yet	1s	128 MB	Judgeable
Milking TimeChoose non-overlapping milking intervals, each separated by at least R rest hours, to maximize the total milk produced over N hours.	Medium6	Dynamic programmingBinary search+2	No attempts yet	1s	128 MB	Judgeable
Gourmet GrazersAssign each cow a distinct grass type whose price and greenness both meet her minimums, minimizing total price; print -1 if impossible.	Medium6	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Cell Phone NetworkGiven a tree of N pastures, choose the fewest vertices so that every vertex is chosen or adjacent to a chosen one.	Medium6	TreeDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Meteor ShowerFind the earliest time for a unit-speed mover to reach any lattice point that no meteor ever destroys, given each meteor's impact time and cross-shaped destruction.	Medium6	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
River CrossingSplit N cows into consecutive groups, each crossing costs M plus the cumulative marginal cost, and add M for every return trip; minimize the total time.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Building the MoatGiven N distinct points with no three collinear, compute the perimeter of their convex hull and print it to two decimal places.	Medium6	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Round NumbersCount integers in [Start, Finish] whose binary form has at least as many zeroes as ones.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
Cow Roller CoasterChoose components that tile [0, L] with no gaps or overlaps, maximizing total fun while keeping total cost within budget B.	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Standing Long JumpRemove exactly m of n interior stones so the smallest gap between consecutive stepping points from 0 to d is as large as possible.	Medium6	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
Face the Right WayChoose a fixed block size K so that flipping blocks of K consecutive cows turns the whole row forward using the fewest operations, breaking ties by smallest K.	Medium6	GreedySimulation+2	No attempts yet	1s	128 MB	Judgeable
Cheapest PalindromeGiven a string and per-letter insertion and deletion costs, find the minimum cost to turn it into a palindrome by adding or removing characters anywhere.	Medium6	Dynamic programmingString+2	No attempts yet	1s	128 MB	Judgeable
Leaking DikeGiven building heights in a row, water pours over a dike on the left at 1 square meter per minute; find how long until a given building's roof sits 1 meter under water.	Medium6	ArraySimulation+2	No attempts yet	1s	128 MB	Judgeable
Party at Hali-BulaGiven a company hierarchy tree, find the largest set of employees with no boss and employee both chosen, and report whether that maximum set is unique.	Medium6	TreeDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Island of LogicGiven statements by islanders who always tell the truth, always lie, or lie only at night, deduce every fact forced across all valid assignments.	Medium6	Brute forceSimulation+2	No attempts yet	1s	128 MB	Judgeable
RailroadGiven train schedules with stop times, find the journey from a start city to a destination leaving no earlier than a given time, minimizing arrival time and then maximizing departure.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
The GameFor each pair of pieces on a grid, decide if an orthogonal path can join them without crossing others, and give the minimum number of straight segments.	Medium6	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Shuffling PatienceSimulate a solitaire game that covers complementary pairs or JQK triples across up to 16 piles, and report the final pile sizes or the overflow card number.	Medium6	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Equivalent Resistance of a Resistor NetworkGiven up to 30 resistors with terminal labels and resistances, compute the equivalent resistance between two points by repeatedly merging series and parallel groups.	Medium6	GraphSimulation+2	No attempts yet	1s	128 MB	Judgeable
IntersectionDecide, for each test case, whether a line segment and an axis-aligned rectangle share at least one point, including degenerate rectangles.	Medium6	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
Alien SecurityGiven a directed graph with entry at room 0 and a target ET room, find the room closest to the target such that every path from 0 to the target passes through it, excluding the target itself.	Medium6	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Trip RoutingGiven a bidirectional weighted map of city pairs, find and print the shortest route between each queried city pair with full leg-by-leg formatting.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Annoying Painting ToolGiven a target black-and-white grid and a fixed r by c flip rectangle, find the minimum number of flips to reach it, or report impossibility.	Medium6	GreedySimulation+2	No attempts yet	1s	128 MB	Judgeable
Economic Phone CallsGiven a chronologically ordered call log with some entries marked important, keep the fewest entries so all important ones stay and the listed year-recovery rule still gives each kept call its original year.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Decorate the WallGiven non-overlapping axis-aligned rectangles on a wall, find the lowest then leftmost position where a new w' by h' rectangle fits without overlapping any of them, or report failure.	Medium6	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Even a Kindergartner Could Solve ThisDecide whether each string over the alphabet {, }, and comma is a valid set by the given grammar, where brace characters can be either delimiters or atoms.	Medium6	StringDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Run Length EncodingEncode each input line with run-length encoding: runs of 2 to 9 repeats become a count plus the character, longer runs split at 9, and everything else is wrapped in 1s with each 1 doubled.	Medium6	StringSimulation+2	No attempts yet	1s	128 MB	Judgeable
Largest Rectangle in a HistogramGiven a histogram of unit-width bars with varying heights, find the area of the largest rectangle that fits inside it, processing several test cases until a 0 terminates input.	Medium6	StackArray+2	No attempts yet	1s	256 MB	Judgeable
Mondrian's DreamCount the number of ways to tile an h by w rectangle (up to 11 by 11) with 2 by 1 dominoes, for several test cases.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
Hike on a GraphThree pieces on a complete edge-colored graph; a piece may move only along an edge whose color matches the edge between the other two, and we want the fewest moves to gather all three on one vertex.	Medium6	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
From Dusk till Dawn (or Vladimir the Vampire)Given nightly train routes between cities with departure and travel hours, find the route that minimizes the number of daytime waits, where a wait costs one litre of blood.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
FroggerGiven n points, find the path from point 1 to point 2 that minimizes the longest edge, and report that minimized maximum edge length.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Ambiguous ResultGiven a parenthesis-free expression of numbers joined by + and *, restore parentheses to find the smallest and largest values it can evaluate to.	Medium6	Dynamic programmingIntervals+2	No attempts yet	1s	128 MB	Judgeable
Arable AreaGiven a lattice polygon, count the unit grid squares fully contained inside it.	Medium6	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
CraneGiven a chain of segments with one joint angle changing per command, report the endpoint coordinates after each change within 0.02 and to two decimals.	Medium6	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
ElectricityGiven an undirected graph, find the maximum number of connected components formed when any single vertex is removed.	Medium6	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Christmas PresentsChoose a subset of children whose total price is at most p, maximizing excitement of chosen minus frustration of unchosen, and output the lexicographically smallest optimal 0/1 string.	Medium6	Dynamic programmingGreedy	No attempts yet	1s	128 MB	Judgeable
Directed mazesGiven a grid maze where each sign permits turns based on arrival direction, find the fewest intersections on a route from the entrance to the goal.	Medium6	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
A Language for ConstantsFor each nonzero integer C, output the shortest sequence of C+1/C-1 to start, then INCR and DBL, that builds C, breaking ties by total runtime with DBL cost T and INCR cost 2T.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Returning BooksTrack which books are on the shelves and which sit at the desk, then on each SHELVE command report where each returned book belongs by comparing author and title in ASCII order.	Medium6	SortingArray+2	No attempts yet	1s	128 MB	Judgeable
Parallelogram CountingGiven n points, count how many 4-point subsets form a parallelogram by pairing points that share a midpoint.	Medium6	Hash mapGeometry+2	No attempts yet	1s	128 MB	Judgeable
ReorganizationGiven each employee's rank in ID order, decide whether a binary hierarchy exists where every non-root has a supervisor with a smaller ID and a better rank.	Medium6	GreedyTree+2	No attempts yet	2s	512 MB	Judgeable
Tree PruningGiven a rooted binary tree with colored nodes, prune subtrees to make the whites minus blacks equal exactly D, minimizing the number of prunes.	Medium6	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Computer Purchase ReturnChoose exactly one component of each of T types so the total cost stays within budget B and the total value is maximized.	Medium6	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Space MinerTravel in straight segments through ordered 3D waypoints; for each planet, check whether any segment passes within distance ri+D of its center, then sum the resources of all planets you can reach at least once.	Medium6	GeometryImplementation+2	No attempts yet	2s	512 MB	Judgeable
Shop and ShipGiven an undirected weighted graph, city-specific pencil prices, and a destination D, find the cheapest price plus shipping cost to get a pencil to D.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
HerdingPlace the fewest traps on a grid of arrows so that a cat starting anywhere and following arrows forever eventually enters a trapped cell.	Medium6	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
CandySplit multiset candies with counts and calorie values into two groups so the two calorie totals differ as little as possible.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
FriendsEach student points to exactly one friend, forming directed cycles; for each query, report whether two students lie on the same cycle and the forward distance between them.	Medium6	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Tin Can TelephoneCount how many polygon buildings touch or cross the straight segment between two windows, where touching a corner or edge blocks the view.	Medium6	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
R & JGiven two ships and n spheres in 3D, count how many spheres the segment between the ships intersects.	Medium6	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
DominoGiven a multiset of dominoes, find the minimum number of extra dominoes to add so all of them (old and new) form one end-to-end chain where touching halves match.	Medium6	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
Return of Space TurtleTwo objects travel closed rectangular paths on a grid; find the minimum distance between them, sampled once per minute at integer times.	Medium6	SimulationMath+2	No attempts yet	1s	128 MB	Judgeable
DuathlonGiven each competitor's running and cycling speeds and a fixed total distance, choose the run and cycle legs so the last competitor wins by the largest margin, or report that no such split exists.	Medium6	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Election NightEach state is already won or has a set of possible winners; decide for every candidate whether they win the electoral college in all, some, or no assignment of undecided states.	Medium6	GreedyMath+2	No attempts yet	1s	128 MB	Judgeable
Extension CordsDecide whether the extension cords can be split into two groups, each long enough to reach a different-circuit outlet from one work location.	Medium6	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Maple RoundupGiven up to 99 points, find the convex hull by repeatedly turning right through the smallest angle, and output its perimeter rounded to two decimals.	Medium6	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Sum of ProductsExpand a polynomial-like expression of variables into a sum of products, then sort each term's letters and sort the terms lexicographically.	Medium6	StringRecursion+2	No attempts yet	1s	128 MB	Judgeable
Mountain PassageFind the minimum count of steps that touch an elevation above the start height, moving on an n by n grid with height changes limited to 2 per step.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
World CupGiven win/draw/loss records for 6 nations in a round-robin group, decide for each of four cases whether some assignment of the 15 match results produces those records.	Medium6	BacktrackingBrute force+2	No attempts yet	1s	128 MB	Judgeable
Stepping on TilesGiven N distinct increasing numbers, find the maximum sum of a 3-or-more element arithmetic subsequence with any common difference, or 0 if none exists.	Medium6	Dynamic programmingHash map+2	No attempts yet	1s	256 MB	Judgeable
Tree IsomorphismGiven two rooted trees in pre-order with '#' closing each node's child list, decide whether the trees are isomorphic ignoring node labels.	Medium6	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable