Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,612 problems

Diamond Inheritance (Large)
Medium5
Graph, Topological sort+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Kingdom Rush (Large)
Medium5
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Recycled Numbers (Large)
Medium5
String, Brute force+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Technology Planning
Medium5
Topological sort, Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Technology Planning
Medium5
Topological sort, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Survivor (Small)
Medium5
Backtracking, Dynamic programming
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Choosing a meeting place (Large)
Medium5
Shortest path, Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Card Shuffle (Large)
Medium5
Simulation, Intervals
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Best coffee (Small)
Medium5
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Morning Coffee (Large)
Medium5
Greedy, Heap+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Theme Park (Large)
Medium5
Simulation, Queue+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Dire Straights (Small)
Medium5
Backtracking, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Killer Word (Small)
Medium5
Simulation, String+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Closing the Loop (Large)
Medium5
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Building a House (Small)
Medium5
Stack, Matrix
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Picking Up Chicks
Medium5
Greedy, Array
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cheating a Boolean Tree (Small)
Medium5
Tree, Dynamic programming
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cheating a Boolean Tree (Large)
Medium5
Dynamic programming, Tree+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Milkshakes (Small)
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Saving the Universe (Large)
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Traffic (Small)
Medium5
Tree, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Roller Coaster
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Theory
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Doki Doki Snack Handout
Medium5
Stack, Simulation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bus Routes
Medium5
Tree, Math+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Seat Assignment
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
0.8s
Memory limit
32 MB
Judgeable
Make It One 2
Medium5
Dynamic programming, BFS+1
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
N-dimensional travel
Medium5
Hash map, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Souvenir
Medium5
Simulation, Queue+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Birthday Presents
Medium5
Sorting, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cheating a Boolean Tree
Medium5
Tree, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Handing out candies
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hosting Contests
Medium5
Greedy, Binary search
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A and B 2
Medium5
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multiple Switches
Medium5
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Double and Add
Medium5
Greedy, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ducks
Medium5
Greedy, Simulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree with the longest diameter
Medium5
Tree, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Movement 3
Medium5
Math, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Powers of Three Walk
Medium5
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Turning A into B
Medium5
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ABCDE
Medium5
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Centipede legs
Medium5
Math, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Intervals of Unique Numbers
Medium5
Two pointers, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Dwarves
Medium5
Graph, Topological sort+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Selling CPUs
Medium5
Dynamic programming, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maze
Medium5
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minimum Swaps
Medium5
Array, Hash map+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Train Line Construction
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Secret Password
Medium5
String matching, Array+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Bits Equalizer
Medium5
Greedy, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lucky Tickets
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fibonacci Chicken
Medium5
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Resort
Medium5
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gas Stations
Medium5
Greedy, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Equal leaf distances
Medium5
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Water Pump
Medium5
Array, Prefix sum
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Contiguous Sum 2
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hidden Anagrams
Medium5
Hash map, String+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Tangsuyuk Game
Medium5
String, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hard Cuts
Medium5
Dynamic programming, Implementation
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Manta Ray
Medium5
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number of arithmetic triples
Medium5
Hash map, Math
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Percolation
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jewelry Store
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Rouba-Monte
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Guess the Number from Divisors and Multiples
Medium5
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Isosceles Cube Triangle
Medium5
Array, Brute force+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Command History
Medium5
Array, Hash map+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Stock exchange
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sum of Factorials
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Grandpa Pepe's Pizza
Medium5
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Short Story Contest
Medium5
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Erasing and Winning
Medium5
Greedy, Stack+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Vampires
Medium5
Probability, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sentence Reduction
Medium5
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Strange Bar
Medium5
Binary search, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sum Decomposition 2
Medium5
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Making the Array Palindromic
Medium5
Two pointers, Greedy+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Alphabet String
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minimum number of islands
Medium5
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Project Panoptes
Medium5
Array, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Make One Square
Medium5
Geometry, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Autocorrelation Function
Medium5
Math, Geometry+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Gather on the Clock
Medium5
Dynamic programming, Intervals
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Cutting into three pieces
Medium5
String, Brute force+1
No attempts yet
Time limit
0.2s
Memory limit
256 MB
Judgeable
m-ary Partitions
Medium5
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Rational Sequence 3
Medium5
Tree, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Robot
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Opening Day 2
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Assignments
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Password
Medium5
Combinatorics, Math
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Grand Opening
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
It's Raining, Man
Medium5
Graph, DFS
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jupiter Orbiter
Medium5
Simulation, Queue+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Abbreviation
Medium5
String, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Weird Measurements (Medium)
Medium5
Array, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Large Weird Measurements
Medium5
Array, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Caki
Medium5
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
HNL
Medium5
Brute force, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Diamond Inheritance (Large)Decide whether any pair of classes in each inheritance DAG has two different inheritance paths between them.	Medium5	GraphTopological sort+1	No attempts yet	5s	512 MB	Judgeable
Kingdom Rush (Large)Find the fewest level completions that earn a 2-star rating on every level when each level needs minimum star counts for its 1-star and 2-star plays.	Medium5	GreedySorting	No attempts yet	5s	512 MB	Judgeable
Recycled Numbers (Large)Count pairs n < m in [A, B] with equal digits where m is a rotation of n with no leading zero, counting each pair once.	Medium5	StringBrute force+1	No attempts yet	5s	512 MB	Judgeable
Technology PlanningFind every goal technology plus its prerequisites and print the smallest valid research order, breaking ties lexicographically.	Medium5	Topological sortGraph	No attempts yet	5s	512 MB	Judgeable
Technology PlanningPlan the smallest set of technologies covering every goal plus its dependencies, then print the lexicographically smallest valid research order.	Medium5	Topological sortGraph+2	No attempts yet	5s	512 MB	Judgeable
Survivor (Small)Pick which foods to eat and in what order, respecting each shelf life, to maximize total survival time.	Medium5	BacktrackingDynamic programming	No attempts yet	5s	512 MB	Judgeable
Choosing a meeting place (Large)Each friend moves at their own speed, so run Dijkstra once per friend and pick the city with the smallest worst arrival time.	Medium5	Shortest pathGraph	No attempts yet	5s	512 MB	Judgeable
Card Shuffle (Large)Find the card at position W after moving the given blocks of a numbered M-card deck to the top C times.	Medium5	SimulationIntervals	No attempts yet	5s	512 MB	Judgeable
Best coffee (Small)Pick one coffee cup per day from kinds with limited cups and expiry days to maximize total satisfaction over K days.	Medium5	GreedySorting	No attempts yet	5s	512 MB	Judgeable
Morning Coffee (Large)Choose one cup per day from day 1 to K so no kind is drunk past its deadline and total satisfaction is largest.	Medium5	GreedyHeap+1	No attempts yet	5s	512 MB	Judgeable
Theme Park (Large)Groups board a coaster holding at most k people in queue order and rejoin the back after riding, and R runs of earnings must be totaled.	Medium5	SimulationQueue+1	No attempts yet	5s	512 MB	Judgeable
Dire Straights (Small)Split the hand into groups of consecutive values to make the shortest group as long as possible.	Medium5	BacktrackingSorting	No attempts yet	5s	512 MB	Judgeable
The Killer Word (Small)Pick the dictionary word that makes Sean miss the most guesses under his order-based guessing rule, breaking ties by dictionary order.	Medium5	SimulationString+1	No attempts yet	5s	512 MB	Judgeable
Closing the Loop (Large)Pick equal numbers of red and blue rope segments to maximize total length minus one centimeter per knot.	Medium5	GreedySorting	No attempts yet	5s	512 MB	Judgeable
Building a House (Small)Find the area of the largest axis-aligned rectangle containing only grass and shrub cells on each grid map.	Medium5	StackMatrix	No attempts yet	5s	512 MB	Judgeable
Picking Up ChicksCount the fewest adjacent swaps so at least K chicks, slowed by slower chicks ahead, reach the barn by time T.	Medium5	GreedyArray	No attempts yet	5s	512 MB	Judgeable
Cheating a Boolean Tree (Small)Given a complete boolean tree with switchable gates, find the minimum number of gate flips so the root evaluates to V.	Medium5	TreeDynamic programming	No attempts yet	5s	512 MB	Judgeable
Cheating a Boolean Tree (Large)Given a complete binary tree of AND/OR gates with fixed leaf values, find the fewest changeable gates to flip so the root equals V, or report IMPOSSIBLE.	Medium5	Dynamic programmingTree+2	No attempts yet	5s	512 MB	Judgeable
Milkshakes (Small)Assign each flavor malted or unmalted so every customer gets a liked type, minimizing malted batches, with at most one malted liked type per customer.	Medium5	GreedyImplementation+2	No attempts yet	5s	512 MB	Judgeable
Saving the Universe (Large)Given a query stream and a set of engines, choose which engine handles each query, never an engine matching the query, to minimize the number of switches.	Medium5	GreedyImplementation+2	No attempts yet	5s	512 MB	Judgeable
Traffic (Small)Given a tree and Q tickets, count how many tickets use each edge along the unique path, then report the edge with the largest count (smallest station pair on ties).	Medium5	TreePrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Roller CoasterFrom a sequence of column heights, delete columns so the survivors strictly decrease then strictly increase (either part may be empty); output the maximum number of survivors.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
String TheoryGiven alternating runs of quote characters, find the largest k for which the whole string is a k-quotation.	Medium5	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
Doki Doki Snack HandoutGiven a queue of numbered students, check whether they can be passed out in order 1 to N using one last-in-first-out holding spot.	Medium5	StackSimulation	No attempts yet	1s	128 MB	Judgeable
Bus RoutesOn a tree with N stops, every ordered pair sends a bus along the unique path; for each stop count how many of the N(N-1) buses halt there, including endpoints.	Medium5	TreeMath+1	No attempts yet	3s	1024 MB	Judgeable
Seat AssignmentAssign seats left to right, each time giving the seat to the still-unseated request with the smallest right endpoint that covers it.	Medium5	GreedySorting+1	No attempts yet	0.8s	32 MB	Judgeable
Make It One 2Find the fewest operations (divide by 3, divide by 2, or subtract 1) turning N into 1, and print the lexicographically smallest shortest path.	Medium5	Dynamic programmingBFS+1	No attempts yet	0.5s	512 MB	Judgeable
N-dimensional travelGiven a walk on an N-dimensional integer grid as a list of coordinate indices and signs, decide whether all visited points, including start and end, are distinct.	Medium5	Hash mapImplementation+2	No attempts yet	2s	512 MB	Judgeable
SouvenirParticipants sit in a circle; stage t removes the t^3-th person counting clockwise from the current host, and you find the last survivor.	Medium5	SimulationQueue+2	No attempts yet	2s	512 MB	Judgeable
Birthday PresentsPick a subset of presents whose price range is below D, maximizing total satisfaction.	Medium5	SortingSliding window+2	No attempts yet	2s	512 MB	Judgeable
Cheating a Boolean TreeIn a tournament-style Boolean tree, flip the fewest changeable AND/OR gates so the root evaluates to V, or report it impossible.	Medium5	TreeDynamic programming	No attempts yet	2s	512 MB	Judgeable
Handing out candiesFor every K, count the ways to choose one candy of each brand 1 through K, and print the total over all K.	Medium5	Dynamic programmingCombinatorics	No attempts yet	2s	512 MB	Judgeable
Hosting ContestsGiven counts of five problem groups, each usable at one of its allowed difficulty slots, find the maximum number of easy-medium-hard contests.	Medium5	GreedyBinary search	No attempts yet	2s	512 MB	Judgeable
A and B 2Given two strings of A and B, decide whether repeatedly appending A or appending B then reversing can turn S into T.	Medium5	StringGreedy+2	No attempts yet	2s	512 MB	Judgeable
Multiple SwitchesGiven N bulbs as Y/N, find the fewest presses of switches that flip multiples to turn all bulbs off, or -1 if impossible.	Medium5	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Double and AddStarting from an all-zero array, find the minimum number of single-element increments and whole-array doublings that produce the target array B.	Medium5	GreedyBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
DucksSplit a string of q,u,a,c,k into the fewest interleaved subsequences, each reading as 'quack' repeated.	Medium5	GreedySimulation+1	No attempts yet	2s	512 MB	Judgeable
Tree with the longest diameterGiven the number of vertices at each level from the root, build a tree realizing those level counts with the maximum possible diameter.	Medium5	TreeGreedy+2	No attempts yet	2s	512 MB	Judgeable
Movement 3Decide whether (x, y) is reachable by moving 3^k right or up on each step k, starting at the origin.	Medium5	MathBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Powers of Three WalkGiven a target point, decide whether it is reachable if stage k moves exactly 3^k in one of the four axis directions.	Medium5	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Turning A into BGiven two equal-length uppercase strings A and B, find the minimum number of moves that bring a chosen character to the front of A so that A becomes B, or -1 if impossible.	Medium5	StringGreedy+2	No attempts yet	2s	512 MB	Judgeable
ABCDEGiven an undirected friendship graph, decide whether it contains a simple path of five distinct vertices, that is, a path with four edges.	Medium5	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Centipede legsGiven n and m notes, choose left and right leg counts summing to n, both at least 1, maximizing how many notes have l_i <= left and r_i <= right, breaking ties by smallest left count.	Medium5	MathPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Intervals of Unique NumbersCount pairs (i, j) where the subarray from i to j has all distinct values, with N up to 100000.	Medium5	Two pointersSliding window+2	No attempts yet	1s	32 MB	Judgeable
DwarvesGiven strict size comparisons between named dwarves, decide whether the statements are mutually consistent.	Medium5	GraphTopological sort+2	No attempts yet	2s	512 MB	Judgeable
Selling CPUsSell up to c CPUs across m ordered merchants, each paying p_i for exactly i CPUs in one deal, to maximize total money.	Medium5	Dynamic programmingGreedy	No attempts yet	2s	512 MB	Judgeable
MazeBob moves through a multi-graph where each letter opens doors with that label; given the letter sequence, compute the probability he reaches room n, choosing uniformly among available matching doors.	Medium5	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Minimum SwapsGiven permutations A and B, find the minimum number of swaps within A that turn it into B.	Medium5	ArrayHash map+2	No attempts yet	1s	64 MB	Judgeable
Train Line ConstructionOn an N by N grid with resident counts and blocked cells, find a 4-direction path between two stations minimizing the sum of cell weights along it.	Medium5	GraphShortest path+2	No attempts yet	1s	64 MB	Judgeable
Secret PasswordGiven two length-N sequences, decide whether one is a cyclic rotation of the other.	Medium5	String matchingArray+2	No attempts yet	1s	64 MB	Judgeable
Bits EqualizerGiven S with 0, 1, ? and T with 0 and 1, find the fewest moves (0 to 1, ? to 0 or 1, swap two positions) to turn S into T, or -1.	Medium5	GreedyString+2	No attempts yet	2s	512 MB	Judgeable
Lucky TicketsCount digit strings of length 2N whose first N digits sum to the same value as the last N digits, modulo 1e9+7.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Fibonacci ChickenGiven N, split it into Fibonacci-derived (people, chicken) pairs whose people counts sum to N, and report the minimum and maximum total chickens.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	128 MB	Judgeable
ResortChoose one-day, 3-day, and 5-day passes over a vacation with blocked days so every open day is covered at minimum cost, where 3 coupons buy a free one-day pass.	Medium5	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Gas StationsGiven road lengths and per-city fuel prices on a line, buy fuel along the way to minimize the total cost of driving from the first city to the last.	Medium5	GreedyArray+2	No attempts yet	2s	512 MB	Judgeable
Equal leaf distancesRaise edge weights in a weighted perfect binary tree so every root-to-leaf path has equal length, minimizing the total weight.	Medium5	TreeGreedy+2	No attempts yet	1s	512 MB	Judgeable
Water PumpPlace one pump in a cell, let water drain toward it from both sides, and find the cell that removes the most water.	Medium5	ArrayPrefix sum	No attempts yet	2s	512 MB	Judgeable
Contiguous Sum 2Find the maximum contiguous subarray sum after optionally deleting at most one element from the sequence.	Medium5	Dynamic programmingArray	No attempts yet	2s	512 MB	Judgeable
Hidden AnagramsGiven two lowercase strings s1 and s2, find the maximum length of a substring of s1 that is an anagram of some substring of s2.	Medium5	Hash mapString+2	No attempts yet	10s	512 MB	Judgeable
Tangsuyuk GameGiven a word of distinct letters, find the shortest memorized cyclic string each player repeats to always say the correct next letter.	Medium5	StringMath+1	No attempts yet	1s	128 MB	Judgeable
Hard CutsFor each w by h rectangle, find the minimum number of integer-sided squares that tile it exactly.	Medium5	Dynamic programmingImplementation	No attempts yet	2s	256 MB	Judgeable
Manta RayFor each data set, count the plankton points that fall inside the rectangle swept by a mouth of width w moving distance t in direction alpha.	Medium5	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Number of arithmetic triplesCount index triples i < j < k where the three values A_i, A_j, A_k form an arithmetic progression.	Medium5	Hash mapMath	No attempts yet	3s	512 MB	Judgeable
PercolationGiven an M by N grid of conducting (0) and blocking (1) cells, decide whether any conducting cell in the top row connects to a conducting cell in the bottom row through edge-adjacent conducting cells.	Medium5	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Jewelry StoreWith unlimited gems of each of N kinds, list all total values obtainable by choosing exactly K gems.	Medium5	Dynamic programmingCombinatorics	No attempts yet	5s	512 MB	Judgeable
Rouba-MonteSimulate a card game where players draw, steal montes, and discard mismatches; report the winners by monte size.	Medium5	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Guess the Number from Divisors and MultiplesGiven A, B, C, D, find the smallest N where A divides N, B does not, N divides C, and N does not divide D, or print -1.	Medium5	Number theoryMath+1	No attempts yet	1s	512 MB	Judgeable
Isosceles Cube TriangleGiven column heights, find the largest h such that some 2h-1 consecutive columns can all be reduced to the shape 1,2,...,h,...,2,1.	Medium5	ArrayBrute force+1	No attempts yet	1s	512 MB	Judgeable
Command HistoryGiven a sequence of positions in a command history, simulate running each command by the nearest occurrence and total the up-arrow presses needed.	Medium5	ArrayHash map+2	No attempts yet	1s	512 MB	Judgeable
Stock exchangeGiven daily prices and a fixed fee per buy, find the maximum total profit when holding at most one share at a time and each share must be sold later.	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Sum of FactorialsGiven N up to 100000, find the fewest factorials (repeats allowed) whose sum equals N.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	512 MB	Judgeable
Grandpa Pepe's PizzaGiven N olive positions on a circle of circumference C, decide whether equal sectors of length C/N can each contain exactly one olive.	Medium5	MathImplementation+1	No attempts yet	2s	512 MB	Judgeable
Short Story ContestGiven words, a max line width C, and max lines per page L, find the fewest pages when each line is packed greedily left to right.	Medium5	GreedyString+1	No attempts yet	2s	512 MB	Judgeable
Erasing and WinningGiven an N-digit number and D, erase exactly D digits so the remaining digits, in order, form the largest possible number. Multiple test cases until 0 0.	Medium5	GreedyStack+2	No attempts yet	2s	512 MB	Judgeable
VampiresGiven two life totals, a hit threshold and a fixed damage, find the probability that vampire 1 wins a turn-based drain fight.	Medium5	ProbabilityDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Sentence ReductionGiven tasks with weekday, start and end times, and point values, pick a non-overlapping set that maximizes total points, and report the per-day breakdown.	Medium5	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
Strange BarGiven N kettle volumes and K people, find the largest integer amount X such that the sum over all kettles of floor(volume / X) is at least K.	Medium5	Binary searchArray+2	No attempts yet	1s	512 MB	Judgeable
Sum Decomposition 2Count ordered K-tuples of integers between 0 and N whose sum is N, modulo 1,000,000,000.	Medium5	Dynamic programmingCombinatorics+1	No attempts yet	1s	512 MB	Judgeable
Making the Array PalindromicMerge adjacent elements (each merge sums them) so the resulting array reads the same forwards and backwards, using the fewest merges. All values are positive.	Medium5	Two pointersGreedy+2	No attempts yet	1s	64 MB	Judgeable
Alphabet StringInsert the fewest lowercase letters into s so that deleting some letters leaves exactly a through z in order.	Medium5	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Minimum number of islandsGiven a grid of land, water, and cloud cells, find the minimum possible number of 4-connected land islands if every cloud can be either land or water.	Medium5	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Project PanoptesGiven n brightness readings and a lower bound p, find the smallest k >= p such that some arithmetic progression with step k lands only on dim days, where dim means below 0.8 times the average; output -1 if none exists.	Medium5	ArrayBrute force+2	No attempts yet	2s	512 MB	Judgeable
Make One SquareGiven three rectangles that can each be rotated 90 degrees, decide whether they can tile one square exactly with no overlaps or gaps.	Medium5	GeometryImplementation+2	No attempts yet	2s	512 MB	Judgeable
Autocorrelation FunctionA piecewise linear function is given by its endpoints; compute the integral of f(x)f(x+r) over the whole line for a given shift r.	Medium5	MathGeometry+2	No attempts yet	8s	512 MB	Judgeable
Gather on the ClockCards sit on a ring; repeatedly stack a card onto its clockwise neighbor for the value difference, and maximize the total score when one card remains.	Medium5	Dynamic programmingIntervals	No attempts yet	8s	512 MB	Judgeable
Cutting into three piecesDecide whether the second string can be cut into three non-empty pieces and reordered to equal the first string, printing the shortest-first valid split.	Medium5	StringBrute force+1	No attempts yet	0.2s	256 MB	Judgeable
m-ary PartitionsCount the partitions of n into powers of m, for up to 1000 queries with n up to 10000.	Medium5	Dynamic programmingMath+2	No attempts yet	2s	512 MB	Judgeable
A Rational Sequence 3Find the rational number at position N in the breadth-first level-order traversal of the Calkin-Wilf-style binary tree rooted at 1/1, where left and right children are p/(p+q) and (p+q)/q.	Medium5	TreeMath+2	No attempts yet	2s	512 MB	Judgeable
RobotGiven a grid with obstacles, a start cell, and a fixed cycling order of the four directions, simulate the robot that moves straight until blocked and report where it stops.	Medium5	SimulationImplementation+2	No attempts yet	1s	256 MB	Judgeable
Opening Day 2Given wok sizes, each cooking uses one or two distinct woks and produces the sum of their sizes; find the minimum number of cookings summing to exactly N.	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
AssignmentsGiven deadlines and scores for N assignments, pick a subset schedulable within their deadlines to maximize total score.	Medium5	GreedySorting+2	No attempts yet	1s	256 MB	Judgeable
PasswordCount n-digit strings over 0-9 that contain every one of the m given digits at least once.	Medium5	CombinatoricsMath	No attempts yet	1s	64 MB	Judgeable
Grand OpeningGiven N bowls to produce and a multiset of wok sizes, each round uses one wok or two distinct woks of equal size, and you must reach exactly N bowls with the fewest rounds.	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
It's Raining, ManGiven a set of distinct cards, decide whether they can be ordered in a row so that each neighbouring pair shares a rank or a suit.	Medium5	GraphDFS	No attempts yet	2s	512 MB	Judgeable
Jupiter OrbiterGiven queues with capacities, sensor writes between downlink windows, and per-window downlink limits, decide whether every queue can be emptied.	Medium5	SimulationQueue+1	No attempts yet	2s	512 MB	Judgeable
AbbreviationScan a text and replace each maximal run of two or more single-capitalized words separated by single spaces with their initials followed by the original run in parentheses.	Medium5	StringSimulation+2	No attempts yet	1s	512 MB	Judgeable
Weird Measurements (Medium)Count the contiguous subarrays whose consecutive differences alternate in sign, with no zero differences allowed.	Medium5	ArrayTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
Large Weird MeasurementsCount all contiguous intervals whose consecutive differences strictly alternate in sign, with any length-1 interval counting as weird.	Medium5	ArrayTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
CakiGiven a list of overtake events, track car positions on a loop to find the final top six finishers.	Medium5	SimulationImplementation	No attempts yet	1s	512 MB	Judgeable
HNLGiven N clubs with points and one final round of matches, list every club that can still finish first under some set of results.	Medium5	Brute forceSorting+1	No attempts yet	1s	128 MB	Judgeable