Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,613 problems

A Walk Together
Medium5
Dynamic programming, Simulation
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cent Savings
Medium5
Dynamic programming, Prefix sum
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Top 25 Poll Comparison
Medium5
Greedy, Hash map
No attempts yet
Time limit
10s
Memory limit
256 MB
Judgeable
Permutation with no spaces
Medium5
Backtracking, Brute force+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Mushroom tractor
Medium5
Hash map, Math
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Piggy Back
Medium5
Shortest path, BFS
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Marathon 2
Medium5
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cow Jog
Medium5
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Learning by Example
Medium5
Sorting, Intervals
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Ancient Dictionary Order
Medium5
Topological sort, Graph+1
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Cow Routing II
Medium5
Brute force, Hash map
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Sandcastle
Medium5
BFS, Simulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Two-Area Database
Medium5
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Censoring
Medium5
String matching, Stack
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Censoring
Medium5
Stack, String matching
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Moocryption
Medium5
Brute force, Matrix+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Pi Day Pie Distribution
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Empire
Medium5
Shortest path, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Honey Butter Chip
Medium5
Dynamic programming, Array
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Window
Medium5
Prefix sum, Brute force
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Color Balls
Medium5
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Square Piece Cut
Medium5
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Maximize Differences
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Sequence Artisan
Medium5
Greedy, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Travel between two islands
Medium5
Union-find, Math
No attempts yet
Time limit
1s
Memory limit
16 MB
Judgeable
Cactus or not
Medium5
DFS, Graph
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Pipes
Medium5
DFS, Graph
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Lucky Cookie Bakery
Medium5
Dynamic programming
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Explosive Materials
Medium5
Graph, BFS+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
The Missing Permutation
Medium5
Greedy, Dynamic programming+1
No attempts yet
Time limit
15s
Memory limit
256 MB
Judgeable
Attendance Award
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Next Unique-Digit Number
Medium5
Backtracking, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Longest Bitonic Subsequence
Medium5
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Criboard Max A
Medium5
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
TV War
Medium5
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Traffic Volume
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Robberies
Medium5
Dynamic programming, Probability
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Guarding the Border
Medium5
Binary search, Greedy+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Cross Country Race
Medium5
Simulation, Greedy+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Base-2 Palindromes
Medium5
Bit manipulation, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Car Game
Medium5
String matching, Array
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Bank Queue
Medium5
Greedy, Heap+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Chasing
Medium5
Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Entertainment Box
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Numbers are Easy
Medium5
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Matrix
Medium5
Shortest path, Graph
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Gimli's Gullet
Medium5
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Song Titles
Medium5
Greedy, Heap+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Number of distinct substrings
Medium5
String matching, Hash map+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jumping Across Logs
Medium5
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Boggle
Medium5
Backtracking, Trie+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Running Steps
Medium5
Combinatorics, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Pyro Tubes
Medium5
Bit manipulation, Hash map
No attempts yet
Time limit
13s
Memory limit
256 MB
Judgeable
Each digit at most twice
Medium5
Backtracking, Greedy+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Fraction to Repeating Decimal
Medium5
Hash map, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Condition of deep sleep
Medium5
Greedy, Sliding window
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Surf
Medium5
Dynamic programming, Sorting+1
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Map Colouring
Medium5
Backtracking, Graph
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Workstation assignment
Medium5
Greedy, Heap+1
No attempts yet
Time limit
10s
Memory limit
256 MB
Judgeable
Factorial Trailing Zeros
Medium5
Binary search, Math
No attempts yet
Time limit
0.5s
Memory limit
256 MB
Judgeable
Feast Coins
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
K-ary Tree
Medium5
Tree, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Black-and-white Square
Medium5
Matrix, Implementation
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Maximal Area
Medium5
Stack, Array
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Preserving the Grid
Medium5
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Fruit Feast
Medium5
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Turning on the lights
Medium5
BFS, Graph
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Radio Contact
Medium5
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Circular Barn (Silver)
Medium5
Dynamic programming, Brute force
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Load Balancing
Medium5
Brute force, Sorting
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Diamond Collector
Medium5
Sorting, Two pointers
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Field Reduction
Medium5
Brute force, Geometry
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Closing the Farm
Medium5
Union-find, Graph
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cleaning the Club Room!
Medium5
Dynamic programming, Prefix sum
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Counting four cycles
Medium5
Graph, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Mr. Kim's Grocery Store (Small)
Medium5
Greedy, Hash map+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Kim Incheon's Grocery Store (Large)
Medium5
Greedy, Hash map+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Robot Rock Band (Small)
Medium5
Hash map, Brute force
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Robot Rock Band (Large)
Medium5
Hash map, Bit manipulation
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
How Many Files
Medium5
Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Sum of submatrix maxima
Medium5
Sliding window, Matrix+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Googol String (Large)
Medium5
Recursion, Bit manipulation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Haircut Queue
Medium5
Binary search, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Barber Shop Queue
Medium5
Binary search, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cube IV (Large)
Medium5
Dynamic programming, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Broken Calculator (Small)
Medium5
Dynamic programming, Recursion+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Parentheses Order (Small)
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Parentheses Order (Large)
Medium5
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Up and Down Sequence
Medium5
Brute force, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Repeater
Medium5
String, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Repeater (Large)
Medium5
String, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cookie Farms
Medium5
Greedy, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Dragon Maze (Small)
Medium5
BFS, Shortest path+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Dragon Maze (Large)
Medium5
BFS, Dynamic programming
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Consonants (Large)
Medium5
String, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Osmos (Small)
Medium5
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Osmos (Large)
Medium5
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bullseye
Medium5
Binary search, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bullseye
Medium5
Math, Binary search
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Manage Your Energy
Medium5
Greedy, Simulation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
A Walk TogetherTwo walkers follow turn-by-turn routes on a grid, and you compute the most blocks they can walk together by waiting and matching identical directed blocks.	Medium5	Dynamic programmingSimulation	No attempts yet	1s	256 MB	Judgeable
Cent SavingsSplit up to 2000 item prices in order into at most d+1 consecutive groups so the sum of each group rounded to the nearest 10 cents is smallest.	Medium5	Dynamic programmingPrefix sum	No attempts yet	5s	512 MB	Judgeable
Top 25 Poll ComparisonSplit two rankings of the same teams into the smallest consecutive groups that hold the same teams and print each size.	Medium5	GreedyHash map	No attempts yet	10s	256 MB	Judgeable
Permutation with no spacesRecover the permutation from 1 to N whose decimal forms concatenate to the given digit string, choosing the lexicographically smallest one on ties.	Medium5	BacktrackingBrute force+1	No attempts yet	1s	256 MB	Judgeable
Mushroom tractorMushrooms appear one per second, and the goal is the earliest second when some row, column, or diagonal contains at least K of them.	Medium5	Hash mapMath	No attempts yet	2s	32 MB	Judgeable
Piggy BackBessie from field 1 and Elsie from field 2 must both reach the barn at field N, walking alone or meeting in one field to share the rest of the trip.	Medium5	Shortest pathBFS	No attempts yet	1s	256 MB	Judgeable
Marathon 2Run checkpoints 1 to N in order while skipping at most K middle checkpoints to minimize total Manhattan distance.	Medium5	Dynamic programming	No attempts yet	1s	256 MB	Judgeable
Cow JogCount the groups of cows that end at the same position after T minutes when no cow can pass the cow ahead.	Medium5	GreedyArray	No attempts yet	1s	256 MB	Judgeable
Learning by ExampleCount how many integer weights from A to B the nearest-neighbor classifier labels as spotted from N labeled training weights.	Medium5	SortingIntervals	No attempts yet	1s	256 MB	Judgeable
Ancient Dictionary OrderDecide whether some alphabet order makes each given word list sorted lexicographically.	Medium5	Topological sortGraph+1	No attempts yet	8s	256 MB	Judgeable
Cow Routing IIFind the cheapest fare from city A to city B using at most two ordered flight routes, paying each used route full fare.	Medium5	Brute forceHash map	No attempts yet	1s	256 MB	Judgeable
SandcastleEach wave washes away every sand cell whose empty count among its eight neighbors reaches its firmness, so count the waves until no cell collapses.	Medium5	BFSSimulation+1	No attempts yet	1s	256 MB	Judgeable
Two-Area DatabaseRead a fixed sequence of data kinds using a one-slot cache that loads at cost c and serves hits for free, and minimize total read cost.	Medium5	Dynamic programming	No attempts yet	1s	256 MB	Judgeable
CensoringRepeatedly delete the first occurrence of T from S, including matches formed by earlier deletions, and print what remains.	Medium5	String matchingStack	No attempts yet	1s	256 MB	Judgeable
CensoringRepeatedly delete the first occurrence of pattern T from string S until none remains and print the result.	Medium5	StackString matching	No attempts yet	1s	256 MB	Judgeable
MoocryptionFind the substitution cipher with no fixed letters that yields the most MOO strings in all eight grid directions.	Medium5	Brute forceMatrix+1	No attempts yet	1s	256 MB	Judgeable
Pi Day Pie DistributionCount the nondecreasing distributions of n pie pieces among k people with each person getting at least one piece.	Medium5	Dynamic programmingCombinatorics	No attempts yet	1s	256 MB	Judgeable
EmpireFind the fastest route from A to B whose total hull damage stays strictly below K.	Medium5	Shortest pathDynamic programming	No attempts yet	1s	256 MB	Judgeable
Honey Butter ChipArrange the M extra bags within the N fixed bags and pick no two adjacent bags to maximize the chip total.	Medium5	Dynamic programmingArray	No attempts yet	5s	256 MB	Judgeable
WindowFind the largest interior grid-aligned square whose border runs only along domino edges and report its size and top-left corner.	Medium5	Prefix sumBrute force	No attempts yet	8s	256 MB	Judgeable
Color BallsFor each ball, add up the sizes of all strictly smaller balls with a different color.	Medium5	SortingPrefix sum+1	No attempts yet	1s	256 MB	Judgeable
Square Piece CutCut an n by m integer-sided rectangle with guillotine cuts into the fewest integer-sided squares.	Medium5	Dynamic programming	No attempts yet	2s	256 MB	Judgeable
Maximize DifferencesReorder the given array so the sum of absolute differences between neighbors is as large as possible.	Medium5	GreedySorting+1	No attempts yet	1s	256 MB	Judgeable
Sequence ArtisanFind the largest product of any contiguous block in an array with values from -2 to 2, then report it modulo 1000000007.	Medium5	GreedyDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
Travel between two islandsAfter each bridge joins two neighboring islands, report how many island pairs are mutually reachable and the total bridge crossings summed over those pairs.	Medium5	Union-findMath	No attempts yet	1s	16 MB	Judgeable
Cactus or notDecide whether a connected undirected graph is a cactus where each vertex lies on at most one simple cycle.	Medium5	DFSGraph	No attempts yet	1s	32 MB	Judgeable
PipesFind every pipe whose removal disconnects the spring network and print them sorted by endpoint numbers.	Medium5	DFSGraph	No attempts yet	2s	32 MB	Judgeable
Lucky Cookie BakeryAssign each dough ball to one of two ovens with different baking times to minimize the time the slower oven finishes.	Medium5	Dynamic programming	No attempts yet	5s	128 MB	Judgeable
Explosive MaterialsSplit conflicting materials into two safe boxes and minimize the fuller box size.	Medium5	GraphBFS+1	No attempts yet	3s	256 MB	Judgeable
The Missing PermutationFill the zeros with the missing values to maximize the length of the longest increasing subsequence.	Medium5	GreedyDynamic programming+1	No attempts yet	15s	256 MB	Judgeable
Attendance AwardCount length-N strings over L, O and A with at most one L and no three consecutive As for each N up to 3000.	Medium5	Dynamic programmingCombinatorics	No attempts yet	1s	256 MB	Judgeable
Next Unique-Digit NumberFind the smallest integer above N that uses no zero and repeats none of the digits 1 to 9, printing 0 when none exists.	Medium5	BacktrackingCombinatorics+1	No attempts yet	1s	256 MB	Judgeable
Longest Bitonic SubsequenceGiven a sequence of up to 1000 numbers, find the length of its longest subsequence that strictly rises then strictly falls.	Medium5	Dynamic programming	No attempts yet	1s	256 MB	Judgeable
Criboard Max APress A, select all, copy, and paste within N keystrokes to show the most As possible.	Medium5	Dynamic programming	No attempts yet	1s	256 MB	Judgeable
TV WarPick non-overlapping weekly TV programs to maximize the total preference score.	Medium5	Dynamic programmingSorting+2	No attempts yet	1s	256 MB	Judgeable
Traffic VolumeCount how many cars came from the left from the unordered times in two boxes with offsets of 500, 1000, and 1500.	Medium5	GreedySorting+1	No attempts yet	1s	256 MB	Judgeable
RobberiesPick a subset of banks that maximizes the stolen money while the combined capture probability stays strictly below the given limit.	Medium5	Dynamic programmingProbability	No attempts yet	1s	256 MB	Judgeable
Guarding the BorderAdd up to M towers anywhere on a circular border of length L so the largest gap between neighboring towers is as small as possible.	Medium5	Binary searchGreedy+1	No attempts yet	3s	256 MB	Judgeable
Cross Country RaceRunners start one minute apart and stick together once a chaser catches the runner ahead, and the task asks how many repeat races the grouped runners need.	Medium5	SimulationGreedy+1	No attempts yet	1s	256 MB	Judgeable
Base-2 PalindromesFind the M-th positive integer whose binary representation reads the same forward and backward and print it in decimal.	Medium5	Bit manipulationMath	No attempts yet	1s	256 MB	Judgeable
Car GameFind the first dictionary word that contains each three-letter plate as a subsequence, or report that none exists.	Medium5	String matchingArray	No attempts yet	2s	256 MB	Judgeable
Bank QueuePick at most one person per minute before each deadline to maximize the total cash collected.	Medium5	GreedyHeap+1	No attempts yet	1s	256 MB	Judgeable
ChasingCompute how many turns pass until a tortoise moving one section per turn and a hare moving two meet on a circular track.	Medium5	Math	No attempts yet	1s	256 MB	Judgeable
Entertainment BoxSchedule the most TV shows on k recorders so no recorder tapes overlapping shows.	Medium5	GreedySorting+1	No attempts yet	2s	256 MB	Judgeable
Numbers are EasyFind the smallest positive multiple of N whose decimal digits are only 0 and 1 for each test case.	Medium5	BFSGraph+1	No attempts yet	1s	256 MB	Judgeable
MatrixCompute each agent's earliest arrival time, then find Neo's shortest safe route to a telephone that beats every agent there.	Medium5	Shortest pathGraph	No attempts yet	2s	256 MB	Judgeable
Gimli's GulletPack unlimited servings of M foods into capacity C for the most calories, breaking ties by the lexicographically smallest serving counts.	Medium5	Dynamic programming	No attempts yet	1s	256 MB	Judgeable
Song TitlesRearrange each title into the lexicographically smallest anagram with no equal adjacent letters, or report IMPOSSIBLE when none exists.	Medium5	GreedyHeap+1	No attempts yet	1s	256 MB	Judgeable
Number of distinct substringsCount how many different contiguous substrings appear in a lowercase string of length up to 1000.	Medium5	String matchingHash map+1	No attempts yet	1s	512 MB	Judgeable
Jumping Across LogsArrange the given log heights in a circle to minimize the largest height gap between neighbors.	Medium5	GreedySorting	No attempts yet	1s	256 MB	Judgeable
BoggleFind every dictionary word that can be spelled on each letter grid with adjacent cells and no cell reused, treating q as qu.	Medium5	BacktrackingTrie+1	No attempts yet	1s	256 MB	Judgeable
Running StepsCount left-right alternating sequences of one-step and two-step strides where both legs use equal counts and twos are at least as many as ones.	Medium5	CombinatoricsMath	No attempts yet	1s	256 MB	Judgeable
Pyro TubesFor each value in a sorted list, count larger list values whose 18-bit patterns differ in at most two bits.	Medium5	Bit manipulationHash map	No attempts yet	13s	256 MB	Judgeable
Each digit at most twiceFind the largest integer L not greater than U whose decimal digits each appear at most twice.	Medium5	BacktrackingGreedy+1	No attempts yet	3s	256 MB	Judgeable
Fraction to Repeating DecimalWrite each given fraction as its decimal form with the shortest nonrepeating part and the repeating block in parentheses.	Medium5	Hash mapMath+1	No attempts yet	1s	256 MB	Judgeable
Condition of deep sleepTurn all N bulbs off with flips of exactly K consecutive bulbs using the fewest presses, or report Insomnia when it is impossible.	Medium5	GreedySliding window	No attempts yet	1s	256 MB	Judgeable
SurfPick waves with no wait-time overlap so the sum of fun points is as large as possible.	Medium5	Dynamic programmingSorting+1	No attempts yet	4s	256 MB	Judgeable
Map ColouringColor each map with the fewest colors so bordering countries differ and print 1 to 4, or many when more are needed.	Medium5	BacktrackingGraph	No attempts yet	5s	256 MB	Judgeable
Workstation assignmentSeat each arriving researcher at a freed workstation that stayed unlocked to save the most unlocks.	Medium5	GreedyHeap+1	No attempts yet	10s	256 MB	Judgeable
Factorial Trailing ZerosFind the smallest N whose factorial has exactly M trailing zeros, or print -1 when no such N exists.	Medium5	Binary searchMath	No attempts yet	0.5s	256 MB	Judgeable
Feast CoinsCount ways to reach total S with owned coins so that every chosen coin value appears the same number of times.	Medium5	Dynamic programmingCombinatorics	No attempts yet	3s	256 MB	Judgeable
K-ary TreeCompute the edge distance for each query pair in a complete K-ary tree with N nodes numbered in breadth-first order.	Medium5	TreeMath	No attempts yet	1s	256 MB	Judgeable
Black-and-white SquareDecide whether the black cells equal the union of some full rows and columns and print the smallest stripe set.	Medium5	MatrixImplementation	No attempts yet	1s	256 MB	Judgeable
Maximal AreaGiven N column heights, find the area of the largest rectangle formed by whole unit squares.	Medium5	StackArray	No attempts yet	2s	256 MB	Judgeable
Preserving the GridPlace d partitions between cells of a 1 by n board holding k horses to maximize cells no horse can reach.	Medium5	GreedySorting	No attempts yet	1s	32 MB	Judgeable
Fruit FeastEat unlimited fruits that add A or B without passing T, using at most one halving, to reach the largest fullness.	Medium5	Dynamic programming	No attempts yet	2s	512 MB	Judgeable
Turning on the lightsBessie walks through lit adjacent rooms to press switches that light new rooms, and every room ever lit counts.	Medium5	BFSGraph	No attempts yet	2s	512 MB	Judgeable
Radio ContactJohn and Bessie each walk or wait along their fixed routes to minimize the summed squared distance until both reach their final points.	Medium5	Dynamic programming	No attempts yet	2s	512 MB	Judgeable
Circular Barn (Silver)Cows waiting at ring doors walk clockwise to fill each room with one cow at the smallest total squared walking distance.	Medium5	Dynamic programmingBrute force	No attempts yet	2s	512 MB	Judgeable
Load BalancingJohn places one vertical and one horizontal fence to minimize the largest cow count in the four regions.	Medium5	Brute forceSorting	No attempts yet	1s	512 MB	Judgeable
Diamond CollectorSort the diamond sizes and pick two disjoint groups with spread at most K to maximize the total count.	Medium5	SortingTwo pointers	No attempts yet	2s	512 MB	Judgeable
Field ReductionYou remove one of N points to minimize the axis-aligned bounding box area of the rest.	Medium5	Brute forceGeometry	No attempts yet	2s	512 MB	Judgeable
Closing the FarmBarns close one by one in a given order, and the task asks after each step whether all open barns remain connected.	Medium5	Union-findGraph	No attempts yet	2s	512 MB	Judgeable
Cleaning the Club Room!Pick exactly M evenings to reset dirt to zero so the sum of daily visitors times dirt since the last cleaning is smallest.	Medium5	Dynamic programmingPrefix sum	No attempts yet	1s	128 MB	Judgeable
Counting four cyclesCount ordered 4-vertex cycles in an undirected graph given as an N by N adjacency matrix with N up to 250.	Medium5	GraphCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Mr. Kim's Grocery Store (Small)Given the sorted pile of 2N mixed normal and discounted price tags, recover the N sale prices.	Medium5	GreedyHash map+1	No attempts yet	5s	512 MB	Judgeable
Kim Incheon's Grocery Store (Large)Given 2N sorted tags that pair N sale prices with regular prices at 4/3 of each sale price, recover the N sale tags.	Medium5	GreedyHash map+1	No attempts yet	5s	512 MB	Judgeable
Robot Rock Band (Small)Count quadruples with one element from each of four lists whose bitwise XOR equals K.	Medium5	Hash mapBrute force	No attempts yet	5s	512 MB	Judgeable
Robot Rock Band (Large)Count quadruples with one element from each of four lists whose bitwise XOR equals K.	Medium5	Hash mapBit manipulation	No attempts yet	7s	512 MB	Judgeable
How Many FilesFrom printed percentage and count pairs, recover the unique total file count that fits every truncated percentage, or report that several fit.	Medium5	Math	No attempts yet	5s	512 MB	Judgeable
Sum of submatrix maximaAdd up the maximum value inside every K by K submatrix of an N by N matrix generated from two arrays.	Medium5	Sliding windowMatrix+1	No attempts yet	20s	1024 MB	Judgeable
Googol String (Large)Answer the Kth character of a recursively defined binary string for each query with K up to 10^18.	Medium5	RecursionBit manipulation	No attempts yet	5s	512 MB	Judgeable
Haircut QueueFind which of B barbers with fixed cutting times serves the Nth customer when each free barber takes the next waiting customer.	Medium5	Binary searchMath	No attempts yet	5s	512 MB	Judgeable
Barber Shop QueueFind which of B barbers with different cutting times serves the Nth customer when ties go to the smallest barber number.	Medium5	Binary searchMath	No attempts yet	5s	512 MB	Judgeable
Cube IV (Large)Find the longest run of consecutive room numbers placed in neighboring cells and report its starting number and length.	Medium5	Dynamic programmingGraph+1	No attempts yet	5s	512 MB	Judgeable
Broken Calculator (Small)Split X into factors typed with working digits only, minimizing the total of digit, multiply, and equals presses.	Medium5	Dynamic programmingRecursion+1	No attempts yet	5s	512 MB	Judgeable
Parentheses Order (Small)Print the k-th valid parentheses string of n pairs in lexicographic order for each test case, or report that it does not exist.	Medium5	Dynamic programmingCombinatorics	No attempts yet	5s	512 MB	Judgeable
Parentheses Order (Large)Given n and k, output the k-th valid parentheses string of n pairs in lexicographic order, or Doesn't Exist! when fewer than k exist.	Medium5	Dynamic programmingCombinatorics+1	No attempts yet	5s	512 MB	Judgeable
Up and Down SequenceCount the fewest adjacent swaps that turn distinct numbers into a sequence that rises to one peak and then falls.	Medium5	Brute forceSorting	No attempts yet	5s	512 MB	Judgeable
The RepeaterEqualize N lowercase strings using only adjacent duplicate insertions and deletions with the fewest moves, or report impossibility.	Medium5	StringSorting+1	No attempts yet	5s	512 MB	Judgeable
The Repeater (Large)Decide whether N lowercase strings can be made identical by duplicating or deleting adjacent equal letters, and report the fewest moves.	Medium5	StringSorting+1	No attempts yet	5s	512 MB	Judgeable
Cookie FarmsStarting at 2 cookies per second, decide how many farms that cost C and add F each to buy before waiting until X cookies are held.	Medium5	GreedyMath	No attempts yet	5s	512 MB	Judgeable
Dragon Maze (Small)Find the fewest-step walk from the entrance to the exit of a cell grid and report the most power gathered on such a route.	Medium5	BFSShortest path+1	No attempts yet	5s	512 MB	Judgeable
Dragon Maze (Large)In a grid with blocked cells, walk from the entrance to the exit in the fewest moves and collect the most power among such walks.	Medium5	BFSDynamic programming	No attempts yet	5s	512 MB	Judgeable
Consonants (Large)Count the substrings of each given name that contain at least n consecutive consonants.	Medium5	StringCombinatorics	No attempts yet	5s	512 MB	Judgeable
Osmos (Small)Starting from size A, sort the other motes and absorb each smaller one, adding helper motes or deleting blockers for the fewest operations.	Medium5	GreedySorting	No attempts yet	5s	512 MB	Judgeable
Osmos (Large)Starting from size A, absorb the sorted motes in order and use the fewest added or removed motes to clear each blocker.	Medium5	GreedySorting	No attempts yet	5s	512 MB	Judgeable
BullseyeStarting from a white circle of radius r, count how many alternating 1cm black rings the paint budget can complete.	Medium5	Binary searchMath	No attempts yet	5s	512 MB	Judgeable
BullseyeMaria starts from inner radius r with t millilitres of paint and paints alternating 1 cm black and white rings; find how many full black rings fit.	Medium5	MathBinary search	No attempts yet	5s	512 MB	Judgeable
Manage Your EnergyAllocate a capped energy reserve that recharges after each activity across fixed-order tasks to maximize value times energy spent.	Medium5	GreedySimulation	No attempts yet	5s	512 MB	Judgeable