Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,610 problems

Gene Shuffle
Medium5
Prefix sum, Hash map
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Keylogger
Medium5
Linked list, Simulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stock Market
Medium5
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Imagine
Medium5
Prefix sum, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Venus Rover
Medium5
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Olympic Avenues
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Clocks
Medium5
Brute force, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
IOIOI
Medium5
String, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fashionista
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
JJOOII
Medium5
String, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Commute Route
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Arranging Go Stones
Medium5
Stack, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Longest Common Substring
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Quality Inspection
Medium5
Implementation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Listing Square Arrangements in Lexicographic Order
Medium5
Backtracking, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum of a Sequence
Medium5
Math, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Good Numbers
Medium5
Hash map, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Drunk Coding
Medium5
Segment tree, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Jollo
Medium5
Brute force, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Klingon Course Levels
Medium5
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pole Position
Medium5
Array, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Odd or Even
Medium5
Greedy, Math+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Supermarket
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Milk Scheduling
Medium5
Graph, Topological sort+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Milk Routing
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Clumsy Cows
Medium5
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Typo
Medium5
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bookshelf
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Islands
Medium5
Sorting, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow IDs
Medium5
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Awkward Digits
Medium5
Brute force, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Beauty Pageant
Medium5
BFS, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Best Parenthesis
Medium5
Stack, Recursion+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hexagonal Pasture Network
Medium5
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bovine Bridge Battle
Medium5
Hash map, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Big Dance
Medium5
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tea Time
Medium5
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Buying Feed, II
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Word Morph
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Relay Race
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building a Fence
Medium5
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pasture Walking
Medium5
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Switching Lights
Medium5
Segment tree, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hay For Sale
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Best Spot
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sand Castle
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Digit Game
Medium5
Dynamic programming, Game theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Cash
Medium5
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Obstacle Course
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Privileged Cows
Medium5
Greedy, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sunscreen
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Construction
Medium5
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Radar Installation
Medium5
Greedy, Intervals+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Construction 2
Medium5
Greedy, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Charm Bracelet
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Contest
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pearl Pairing
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Loathesome Hay Baler
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Travelling
Medium5
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Munching
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cows on Skates
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fence Repair
Medium5
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tallest Cow
Medium5
Greedy, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Managing Allowance
Medium5
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
ATM PIN Theft
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chessboard Dance
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crazy Search
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prime Land
Medium5
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Packets
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Extended Lights Out
Medium5
Brute force, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Entropy
Medium5
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Computer
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stockbroker Grapevine
Medium5
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fact
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Extrapolation Using a Difference Table
Medium5
Math, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Call Forwarding
Medium5
Simulation, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Slurpys
Medium5
Recursion, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Power Shortage
Medium5
Minimum spanning tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Broken Keyboard
Medium5
Sliding window, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
El Dorado
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Automatic Typo Correction
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Basic Wall Maze
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Wine Trading in Gergovia
Medium5
Greedy, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
106 Miles to Chicago
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Sierpinski Fractal
Medium5
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Code the Tree
Medium5
Tree, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Decode the Tree
Medium5
Tree, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Anagram Groups
Medium5
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quad Tree
Medium5
Recursion, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Friends
Medium5
String, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Team Queue
Medium5
Queue, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
France '98
Medium5
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Solving Linear Equations
Medium5
Math, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Humble Numbers
Medium5
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rhinoceros Beetle
Medium5
Implementation, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Collatz Conjecture
Medium5
Simulation, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Encryption
Medium5
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
God Save the i-th Queen
Medium5
Array, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Storehouse
Medium5
Greedy, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sea Battle
Medium5
Implementation, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Gene ShuffleTwo permutations of 1..N are given; split [1,N] into the shortest pieces where each piece holds the same set of genes in both. - use plain English	Medium5	Prefix sumHash map	No attempts yet	1s	128 MB	Judgeable
KeyloggerA log of typed keys, arrow moves, and backspaces in a text field must be replayed to recover the final password.	Medium5	Linked listSimulation+1	No attempts yet	1s	256 MB	Judgeable
Stock MarketFind the contiguous subarray with the largest sum and report its 1-based start and end indices, breaking ties by smallest start then smallest end.	Medium5	Dynamic programmingGreedy	No attempts yet	1s	256 MB	Judgeable
ImagineMaintain a 1024x1024 grid that starts as a checkerboard and process stickers plus rectangle queries for counts of each letter.	Medium5	Prefix sumArray+2	No attempts yet	1s	256 MB	Judgeable
Venus RoverChoose which stones to collect so total value is maximized, given limits on time and total lifted mass.	Medium5	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
Olympic AvenuesGiven an undirected weighted graph with N up to 50, find the shortest path from S to F and, among ties, print the lexicographically smallest site sequence.	Medium5	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
The ClocksGiven nine clock dials and nine moves that each rotate a fixed subset of dials by 90 degrees, find the shortest move sequence that sets every dial back to 12 o'clock.	Medium5	Brute forceBacktracking+2	No attempts yet	1s	256 MB	Judgeable
IOIOICount the occurrences of the alternating string P_N (N+1 I's and N O's) as a substring of S, counting overlaps.	Medium5	StringSliding window+2	No attempts yet	1s	256 MB	Judgeable
FashionistaFor each day pick any clothing whose temperature range covers that day's high, maximizing the sum of absolute flashiness differences between consecutive days.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
JJOOIIFind the largest k such that k J's, then k O's, then k I's appear consecutively in the given string.	Medium5	StringPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Commute RouteCount monotone lattice paths from (1,1) to (w,h) that never turn at two consecutive intersections, modulo 100000.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Arranging Go StonesStones are added one by one; each even-indexed stone of a new color replaces the trailing run of the opposite color, and we count the white stones that remain.	Medium5	StackSimulation+2	No attempts yet	1s	128 MB	Judgeable
Longest Common SubstringGiven two uppercase strings of length up to 4000, find the length of the longest substring that occurs contiguously in both.	Medium5	Dynamic programmingString+2	No attempts yet	2s	256 MB	Judgeable
Quality InspectionGiven triples of parts (one of each type) with PASS or FAIL results, deduce for every part whether it is certainly good, certainly broken, or undetermined.	Medium5	ImplementationBrute force+1	No attempts yet	1s	128 MB	Judgeable
Listing Square Arrangements in Lexicographic OrderList every partition of n whose parts are non-increasing, and print the sequences in decreasing lexicographic order.	Medium5	BacktrackingRecursion+2	No attempts yet	1s	128 MB	Judgeable
Sum of a SequenceGiven an N by N table holding Ai+Aj for every pair of distinct indices and 0 on the diagonal, recover the original positive sequence A.	Medium5	MathArray+2	No attempts yet	1s	256 MB	Judgeable
Good NumbersCount the elements A_i that equal the sum of three elements appearing earlier in the sequence, where the same earlier element may be reused.	Medium5	Hash mapBrute force+2	No attempts yet	1s	128 MB	Judgeable
Drunk CodingMaintain a sequence under point updates and answer range-product sign queries (+/-/0) for each test case until EOF.	Medium5	Segment treePrefix sum+2	No attempts yet	1s	256 MB	Judgeable
JolloGiven the Princess's three cards and two of the Prince's, find the smallest unused third card that lets the Prince win at least two rounds against any order of play.	Medium5	Brute forceGreedy+2	No attempts yet	1s	128 MB	Judgeable
Klingon Course LevelsPick a score threshold T that splits every division into basic and advanced groups, minimizing the sum over divisions of \|basic - advanced\|. Output that minimum.	Medium5	SortingPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Pole PositionGiven the current race order of N cars with each car's position change from the start, reconstruct the starting grid or report that no valid grid exists.	Medium5	ArraySorting+2	No attempts yet	1s	128 MB	Judgeable
Odd or EvenPair each red number with a blue number to minimize how many pairs sum to an even value, since Mary wins those.	Medium5	GreedyMath+2	No attempts yet	3s	128 MB	Judgeable
SupermarketGiven a shopping list and products in path order, buy the list items in order from later positions at minimum total cost, or report impossible.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Milk SchedulingGiven task durations and precedence constraints that form a DAG, find the minimum makespan when unlimited workers milk cows in parallel.	Medium5	GraphTopological sort+2	No attempts yet	1s	128 MB	Judgeable
Milk RoutingPick a single path from node 1 to node N minimizing latency plus X divided by the path's bottleneck capacity, and floor the result.	Medium5	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Clumsy CowsGiven an even-length string of parentheses, find the minimum number of characters to flip so the string becomes balanced.	Medium5	GreedyString+2	No attempts yet	1s	128 MB	Judgeable
TypoGiven a bracket string with at most one typo, count how many single-character flips turn it into a valid balanced bracket string.	Medium5	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
BookshelfPartition the books in order into shelves whose widths sum to at most L, minimizing the total of each shelf's maximum height.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
IslandsGiven heights along a line, find the maximum number of separate exposed segments at any single rising water level.	Medium5	SortingArray+2	No attempts yet	1s	128 MB	Judgeable
Cow IDsFind the N-th smallest binary number that has exactly K one-bits and no leading zeros, then print it in binary.	Medium5	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
Awkward DigitsGiven a binary string and a ternary string that each differ from the true base-2 and base-3 forms of N in exactly one digit, find N.	Medium5	Brute forceMath+2	No attempts yet	1s	128 MB	Judgeable
Cow Beauty PageantGiven a grid with exactly two connected X regions, find the minimum number of dots to paint so the two regions become one.	Medium5	BFSGraph	No attempts yet	1s	128 MB	Judgeable
Best ParenthesisGiven a balanced parenthesis string encoded as 0/1 values, compute its recursively defined score modulo 12345678910.	Medium5	StackRecursion+2	No attempts yet	1s	256 MB	Judgeable
Hexagonal Pasture NetworkGiven a hexagon-shaped grid of pastures, count and list all pastures at exact distance L from start H using BFS.	Medium5	GraphBFS+1	No attempts yet	1s	128 MB	Judgeable
Bovine Bridge BattleCount sets of four points that are symmetric about some center, where each point pairs with its 180-degree rotation partner.	Medium5	Hash mapGeometry+2	No attempts yet	1s	128 MB	Judgeable
The Big DanceRepeatedly split the interval 1..N at the middle (front group gets the extra when odd), pairing cows when a group has exactly two, and add each pair's product to a running sum.	Medium5	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
Tea TimeStarting from a graph of known meetings, two cows meet whenever they share a mutual friend, and after all rounds settle, answer queries about whether each pair has met.	Medium5	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
Buying Feed, IIPick up to K pounds of feed from stores along a line, paying each store's price plus transport cost of distance carried, and minimize the total.	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Word MorphGiven a dictionary of equal-length words, find the fewest one-letter changes needed to turn the start word into the end word through valid words.	Medium5	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Relay RaceEach cow runs one lap, then signals other cows to start; find the time when the last cow finishes, ignoring repeat signals.	Medium5	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Building a FenceCount the ordered ways to cut a plank of length N into four positive integer pieces whose longest piece is strictly shorter than the other three combined.	Medium5	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
Pasture WalkingGiven a weighted tree with N vertices and Q queries, find the path length between each queried pair of vertices.	Medium5	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Switching LightsMaintain a binary array of N lights under M range-toggle and range-count operations, and print each query result.	Medium5	Segment treeArray+1	No attempts yet	1s	128 MB	Judgeable
Hay For SaleGiven a wagon capacity and a list of hay bale volumes, find the largest total volume not exceeding the capacity that can be formed by choosing whole bales.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Best SpotGiven a weighted undirected graph and a set of favorite vertices, find the vertex whose average shortest-path distance to all favorites is smallest, breaking ties by smallest index.	Medium5	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Sand CastleGiven current merlon heights and a multiset of target heights in any order, pair them to minimize the total cost of raising and lowering, where raising costs X and lowering costs Y.	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Cow Digit GameFor each starting number, players alternately subtract its largest or smallest nonzero digit, and the player who reaches 0 wins; decide if the first player wins.	Medium5	Dynamic programmingGame theory+2	No attempts yet	1s	128 MB	Judgeable
Cow CashCount the number of unordered ways to make an amount N using V coin denominations, where each coin can be used any number of times.	Medium5	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Obstacle CourseOn an N by N grid with blocked tiles, find a walk from A to B that minimizes the number of 90-degree turns; start and end directions are free.	Medium5	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Privileged CowsGiven a sequence of 1s, 2s, and 3s, find the minimum number of arbitrary swaps needed to group all 1s first, then all 2s, then all 3s.	Medium5	GreedyArray+2	No attempts yet	1s	128 MB	Judgeable
SunscreenEach cow accepts an SPF interval, each bottle has an SPF value and capacity; assign bottles to maximize the number of cows covered.	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
String ConstructionRepeatedly take the leftmost or rightmost character of S and append it to T; among all such T, output the lexicographically smallest, wrapping lines at 80 characters.	Medium5	GreedyString+2	No attempts yet	1s	128 MB	Judgeable
Radar InstallationEach island on the sea side of a line must be covered by radars of reach d placed on the line, so find the minimum number of placements or report -1 if some island is unreachable.	Medium5	GreedyIntervals+2	No attempts yet	1s	128 MB	Judgeable
String Construction 2Build the lexicographically smallest string by repeatedly taking either the first or last character of the remaining string and appending it, with ties broken by comparing inward.	Medium5	GreedyTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
Charm BraceletChoose a subset of N charms, each with a weight and a desirability, so that total weight stays within M and total desirability is maximized.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Cow ContestGiven the winners of head-to-head matches, count how many cows have a skill rank that is fully forced by the results.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Pearl PairingGiven counts of each pearl color, output the canonical pairing that matches the pearl at position i with the pearl at position i + N/2 in sorted order.	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
The Loathesome Hay BalerRollers touch when center distance equals the sum of radii; find the path from the drive roller to the take-off roller and sum the absolute speeds, truncated.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Cow TravellingCount the number of walks of exactly T steps on a grid from a start cell to a target cell, where each step moves to a vertically or horizontally adjacent open cell.	Medium5	Dynamic programmingMatrix+2	No attempts yet	1s	128 MB	Judgeable
MunchingFind the length of a shortest grid path from the cow to the barn through grass, then report the number of grass squares munched along it.	Medium5	BFSGraph+2	No attempts yet	1s	256 MB	Judgeable
Cows on SkatesFind a shortest orthogonal path from (1,1) to (R,C) through open grid cells, breaking ties by the lexicographically smallest sequence of cells.	Medium5	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Fence RepairSplit one board into N planks of given lengths; each cut costs the length of the piece being cut, so find the minimum total cost.	Medium5	GreedyHeap+2	No attempts yet	1s	128 MB	Judgeable
Tallest CowGiven the tallest cow's height and index plus pairs where cow a sees cow b, find each cow's maximum possible height consistent with all observations.	Medium5	GreedyPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Managing AllowanceFind the smallest fixed withdrawal amount K so that the N daily costs can be covered using exactly M withdrawals, counting forced top-ups and optional extra ones.	Medium5	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
ATM PIN TheftGiven a sequence of observed key presses (digits and at most one backspace), count the four-digit PINs that could produce exactly that sequence of pressed keys.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Chessboard DanceSimulate a beetle on an 8x8 board following move and turn commands, pushing chains of pieces that may fall off the board.	Medium5	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Crazy SearchCount how many distinct length-N substrings appear in a given text, where the text uses characters from an alphabet of size NC.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Prime LandGiven an integer x in prime-base form (prime powers in decreasing order), print the same representation for x - 1.	Medium5	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
PacketsGiven counts of 1x1 through 6x6 square tiles, find the minimum number of 6x6 parcels needed to pack them all.	Medium5	GreedyImplementation+2	No attempts yet	1s	128 MB	Judgeable
Extended Lights OutGiven a 5 by 6 Lights Out board, find the unique set of button presses that turns every light off, then print the press grid.	Medium5	Brute forceBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
EntropyFor each line of text, print the fixed 8-bit ASCII bit length, the optimal prefix-free Huffman bit length, and the compression ratio rounded to one decimal.	Medium5	GreedyHeap+2	No attempts yet	1s	128 MB	Judgeable
String ComputerCompute the minimum number of single-character insert, delete, or change operations needed to turn one string into another.	Medium5	Dynamic programmingString+2	No attempts yet	1s	128 MB	Judgeable
Stockbroker GrapevineFor each directed weighted graph, find the vertex whose shortest paths reach every other vertex, minimizing the maximum distance; print it and that time, or disjoint.	Medium5	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
FactFor each N up to 10000, find the last non-zero digit of N! and print it with N right-aligned in a field of width 5.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Extrapolation Using a Difference TableExtend a sequence by k steps using a polynomial difference table, always assuming the highest-order differences stay constant, and print the (n+k)-th term.	Medium5	MathDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Call ForwardingGiven timestamped call forwarding rules, follow each call through the active chain, printing the final extension or 9999 if a loop is entered.	Medium5	SimulationHash map+2	No attempts yet	1s	128 MB	Judgeable
SlurpysGiven up to 10 short strings, decide whether each one is a Slurpy, meaning a Slimp followed by a Slump under the recursive grammar in the statement.	Medium5	RecursionString+2	No attempts yet	1s	128 MB	Judgeable
Power ShortageGiven a connected weighted undirected graph, keep a subset of roads so every pair of houses stays connected while maximizing the total length of removed roads.	Medium5	Minimum spanning treeGraph+2	No attempts yet	1s	256 MB	Judgeable
Broken KeyboardFor each test case, find the length of the longest substring of the sentence that contains at most m distinct characters.	Medium5	Sliding windowString+2	No attempts yet	1s	128 MB	Judgeable
El DoradoCount the increasing subsequences of length exactly k in a sequence of n distinct numbers, for several test cases.	Medium5	Dynamic programmingArray+1	No attempts yet	1s	128 MB	Judgeable
Automatic Typo CorrectionGiven a dictionary, classify each queried word as correct, a misspelling of the first similar dictionary word, or unknown, using three specific edit types.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Basic Wall MazeGiven a 6 by 6 grid, three blocking walls, a start and an end square, print the lexicographically smallest shortest path using N, E, S, W moves.	Medium5	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Wine Trading in GergoviaGiven net wine demands along a line summing to zero, find the minimum total transport cost (one unit per bottle per adjacent step).	Medium5	GreedyPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
106 Miles to ChicagoGiven a graph where each edge has a percent probability of staying uncaught, find the path from node 1 to node n that maximizes the product of these probabilities.	Medium5	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
The Sierpinski FractalDraw the outline of a depth-n Sierpinski triangle in ASCII, 2^n rows tall, with no trailing spaces and blank lines between the test cases.	Medium5	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
Code the TreeParse a parenthesized tree description, then repeatedly remove the smallest-numbered leaf and print its neighbor to build the Prufer code.	Medium5	TreeImplementation+2	No attempts yet	1s	128 MB	Judgeable
Decode the TreeGiven a Prüfer code, rebuild the labeled tree on n vertices and print it as a canonical rooted word with children sorted by number.	Medium5	TreeHeap+2	No attempts yet	1s	128 MB	Judgeable
Anagram GroupsGroup distinct words that are anagrams of each other, then print the five largest groups sorted by size and smallest word.	Medium5	Hash mapSorting+2	No attempts yet	1s	128 MB	Judgeable
Quad TreeDecode a quad tree string into an n by n black and white image, then print each row as XBM hexadecimal bytes.	Medium5	RecursionDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
FriendsEvaluate set expressions over uppercase letters using union, intersection, and difference, where * binds tighter than + and - and equal operators left-associate.	Medium5	StringStack+2	No attempts yet	1s	128 MB	Judgeable
Team QueueSimulate a team queue where each new element cuts in behind its own teammates, if any, and otherwise joins the tail; print every dequeued element.	Medium5	QueueHash map+2	No attempts yet	1s	128 MB	Judgeable
France '98Given win probabilities for every pair of 16 teams and a fixed bracket, compute each team's probability of winning the single-elimination tournament.	Medium5	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
Solving Linear EquationsParse each linear equation written in a recursive grammar with parentheses and multiplication, then report no, infinite, or the unique solution rounded to six decimals.	Medium5	MathRecursion+2	No attempts yet	1s	128 MB	Judgeable
Humble NumbersFor each n up to 5842, print the nth number whose only prime factors are 2, 3, 5, or 7, formatted with the correct English ordinal suffix.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	128 MB	Judgeable
Rhinoceros BeetleGiven shared community cards and each player's two hole cards, evaluate every player's best five-card poker hand and print the indices of all winners.	Medium5	ImplementationSorting+2	No attempts yet	2s	128 MB	Judgeable
Collatz ConjectureFor each pair A and B, generate both Collatz sequences up to 1 and find the first value they share, reporting its index in each sequence.	Medium5	SimulationHash map+2	No attempts yet	1s	128 MB	Judgeable
String EncryptionClean the plaintext (drop spaces, uppercase), then invert the given transposition decryption rule to produce the matching ciphertext.	Medium5	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
God Save the i-th QueenGiven a board and placed queens, count empty squares not sharing a row, column, or diagonal with any queen.	Medium5	ArrayHash map+2	No attempts yet	1s	128 MB	Judgeable
StorehouseGiven a sequence of truck cargo requests and B bays, decide which bay holds which cargo type to minimize the number of loads, assuming optimal offline knowledge.	Medium5	GreedyHash map+1	No attempts yet	1s	128 MB	Judgeable
Sea BattleCount rectangular ships of '#' cells on a grid, verify no two touch even diagonally, and report bad placement if the ships are not valid rectangles.	Medium5	ImplementationArray+2	No attempts yet	1s	128 MB	Judgeable