Interview warm-up

Short whiteboard warmups

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Still being built. Things may change

Total results4,881 problems

Board Game
Easy3
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Weight Loss
Easy3
Array, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Permutation
Easy3
Array, Hash map
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cutting the Tape
Easy3
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crossing Out Numbers
Easy3
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Consecutive Girls
Easy3
Sliding window, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gym
Easy3
Math, Number theory
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cords
Easy3
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Circuits
Easy3
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cards
Easy3
Queue, Simulation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Score Chart
Easy3
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pocket Money
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stock Price
Easy3
Stack, Array
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Perfect Memory
Easy3
Math, Array
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
New Year's Eve Party Log
Easy3
Greedy, Prefix sum
No attempts yet
Time limit
25s
Memory limit
128 MB
Judgeable
Konduktor
Easy3
Math, Simulation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Intervals
Easy3
Intervals, Sorting
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hektor's Test Answers
Easy3
Simulation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Class Pairings
Easy3
Combinatorics, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Stone Game
Easy3
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Garden Trouble
Easy3
Sliding window, Two pointers
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Encoding
Easy3
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Palindrome
Easy3
Brute force, String+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Chemical Products
Easy3
Brute force, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Password
Easy3
Combinatorics, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ducci Sequence
Easy3
Simulation, Hash map
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gas
Easy3
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stuttering Strings
Easy3
Backtracking, Recursion+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Circular Sequence
Easy3
String, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lagno
Easy3
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Recovering the Input Numbers
Easy3
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Hunter
Easy3
Binary search, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Work at a Library Is Tough
Easy3
Brute force, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rectangle Coloring
Easy3
Union-find, Geometry
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Parentheses
Easy3
Stack
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cross Country
Easy3
Simulation, Hash map
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Goldbach's Conjecture
Easy3
Number theory, Two pointers
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Iris (Password)
Easy3
Greedy, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fence
Easy3
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Candy-Sharing Game
Easy3
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
6174
Easy3
Simulation, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coin Game
Easy3
Brute force, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lexicographic rank of a permutation
Easy3
Combinatorics, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Primality Test
Easy3
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Adding 1, 2, and 3
Easy3
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The Suspects
Easy3
Union-find
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hauling material
Easy3
Shortest path, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Function run fun
Easy3
Dynamic programming, Recursion
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Approximate String Matching
Easy3
String matching, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jumble Match
Easy3
Sliding window, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Taxi Routes
Easy3
Dynamic programming, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Inviting the Village Chief
Easy3
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Virus Replication
Easy3
String, Two pointers
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sudoku Grading
Easy3
Implementation, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Even More Dice
Easy3
Backtracking, Recursion
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Robot in a Maze
Easy3
BFS, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The real message
Easy3
Simulation, String
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Paying Off the Debt
Easy3
Simulation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Chromosome
Easy3
String matching, String
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Fegla and the Bed Bugs
Easy3
Binary search, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fundraised
Easy3
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
It Is Cold
Easy3
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Eligibility
Easy3
Hash map, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crank
Easy3
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fashion King Haebin
Easy3
Combinatorics, Hash map
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String LD
Easy3
String, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Password Policy Requirement
Easy3
Sliding window, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Calculate the Fence Needed
Easy3
Hash map, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Largest Pairwise GCD
Easy3
Number theory, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Round Robin
Easy3
Simulation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sort Me
Easy3
Sorting, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ballot Analyzing Device
Easy3
Implementation, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Padovan Sequence
Easy3
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Islands in the Data Stream
Easy3
Simulation, Stack
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Strahler order
Easy3
Topological sort, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Politics
Easy3
Sorting, Hash map
No attempts yet
Time limit
15s
Memory limit
256 MB
Judgeable
Generations of Tribbles
Easy3
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Languages
Easy3
Hash map, String
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Football
Easy3
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Between the Mountains
Easy3
Two pointers, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Goldilocks and the N Cows
Easy3
Sorting, Intervals
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lucky Numbers
Easy3
Brute force, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Equal Sum Sets
Easy3
Dynamic programming, Combinatorics
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Maximum Word Frequency
Easy3
Hash map, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
GCD Sum
Easy3
Number theory, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Meeting Room Arrangement
Easy3
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
BABBA
Easy3
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stone Game
Easy3
Dynamic programming, Game theory
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stone Game 2
Easy3
Game theory, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stone Game 3
Easy3
Dynamic programming, Game theory
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stone Game 4
Easy3
Dynamic programming, Game theory
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stone Game 6
Easy3
Game theory, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Original Number of Medallions
Easy3
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sifar
Easy3
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Who you know
Easy3
Shortest path, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Sultan's Chapati
Easy3
Simulation, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rainforest Canopy
Easy3
DFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Charles Babbage's Difference Engine
Easy3
Simulation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Surface Area
Easy3
Simulation, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bi-coloring
Easy3
BFS, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Board GameStarting on field 1, move forward 1 to 6 fields per step to reach field n while collecting the largest possible sum of visited values.	Easy3	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
Weight LossFind the largest weight drop from an earlier day to a later day over all contiguous stretches.	Easy3	ArrayGreedy	No attempts yet	1s	128 MB	Judgeable
PermutationCheck whether n given integers contain each number from 1 to n exactly once and print TAK or NIE.	Easy3	ArrayHash map	No attempts yet	1s	128 MB	Judgeable
Cutting the TapeSplit the row of integers into two nonempty parts so the absolute difference of the two part sums is as small as possible.	Easy3	Prefix sumArray	No attempts yet	1s	128 MB	Judgeable
Crossing Out NumbersCross out as few numbers as possible so the numbers left behind read 1 to k in order.	Easy3	GreedyArray	No attempts yet	1s	128 MB	Judgeable
Consecutive GirlsFind the fewest boys to remove so that k girls stand side by side in a row of n boys and girls.	Easy3	Sliding windowPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
GymCount the integers from 1 to n that are multiples of a or of b.	Easy3	MathNumber theory	No attempts yet	1s	128 MB	Judgeable
CordsPartition the row of cords into the maximum number of contiguous groups with total length at least w.	Easy3	GreedyArray	No attempts yet	1s	128 MB	Judgeable
CircuitsPick the most cables whose total battery voltage does not exceed their total wire tolerance.	Easy3	SortingGreedy+1	No attempts yet	1s	128 MB	Judgeable
CardsApply k top-to-bottom card moves in order and report the number on top of the deck.	Easy3	QueueSimulation	No attempts yet	1s	128 MB	Judgeable
The Score ChartGiven a sequence of 0s, 1s, and 2s, find the length of the longest subsequence that never decreases.	Easy3	Dynamic programmingArray	No attempts yet	1s	128 MB	Judgeable
Pocket MoneyFor each test case, compare the sum and the product of the given numbers and print which is larger or whether they tie.	Easy3	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Stock PriceFor each position find the index of the first later price that is higher, or -1 when no such price exists.	Easy3	StackArray	No attempts yet	2s	128 MB	Judgeable
Perfect MemorySplit an even-length integer sequence into a palindrome and an antipalindrome that add up to it, or print NIE when parity forbids it.	Easy3	MathArray	No attempts yet	2s	128 MB	Judgeable
New Year's Eve Party LogCount the fewest entries and exits to add so the guest count never drops below zero and ends at zero.	Easy3	GreedyPrefix sum	No attempts yet	25s	128 MB	Judgeable
KonduktorCount how many times each of N compartments is visited during the first K steps of a back-and-forth walk starting at compartment 1.	Easy3	MathSimulation	No attempts yet	2s	128 MB	Judgeable
IntervalsCount the integers covered by at least one of N closed intervals in each test set.	Easy3	IntervalsSorting	No attempts yet	2s	128 MB	Judgeable
Hektor's Test AnswersFor each N, print the N-th letter of Hektor's 12-letter cycle over A to D formed by two steps forward and one step back.	Easy3	SimulationMath	No attempts yet	1s	128 MB	Judgeable
Class PairingsCount the ways to split N students into pairs for each test case and print the result modulo 1000.	Easy3	CombinatoricsMath	No attempts yet	1s	128 MB	Judgeable
The Stone GamePlayers alternately remove 1 to K of N stones, and the player taking the last stone wins each test case.	Easy3	Game theoryMath	No attempts yet	1s	128 MB	Judgeable
Garden TroubleFind the longest contiguous segment of the garden that holds at most K chestnut trees.	Easy3	Sliding windowTwo pointers	No attempts yet	1s	128 MB	Judgeable
EncodingCount binary strings of length n that start with 1 and contain no adjacent ones for up to 100 queries.	Easy3	Dynamic programmingCombinatorics	No attempts yet	1s	128 MB	Judgeable
PalindromeFrom the given words, pick two at different positions so their concatenation is a palindrome and report the lexicographically smallest one.	Easy3	Brute forceString+1	No attempts yet	1s	256 MB	Judgeable
Chemical ProductsGiven stocks of chemicals A, B, and C plus prices for products AB, BC, and CA, compute the maximum profit from pairwise mixing.	Easy3	Brute forceGreedy	No attempts yet	1s	128 MB	Judgeable
PasswordFind the K-th password in lexicographic order whose letters appear in the same column of both 6 by 5 grids, or print NO.	Easy3	CombinatoricsSorting+1	No attempts yet	1s	128 MB	Judgeable
Ducci SequenceRepeatedly replace each entry with the absolute difference of adjacent entries and report whether the tuple reaches all zeros or loops.	Easy3	SimulationHash map	No attempts yet	1s	128 MB	Judgeable
GasYou split M integer units across n tubes with linear outputs so every tube yields the same gas amount, or report 0 when impossible.	Easy3	Brute forceMath	No attempts yet	1s	128 MB	Judgeable
Stuttering StringsFor each input case, the program prints every length-n string over * and ! whose runs stay within the given limits, in lexicographic order with * first.	Easy3	BacktrackingRecursion+1	No attempts yet	1s	128 MB	Judgeable
Circular SequenceFind the lexicographically smallest rotation of each given circular DNA string.	Easy3	StringBrute force	No attempts yet	1s	128 MB	Judgeable
LagnoCount the most white pieces a single black move flips on an 8 by 8 Othello board.	Easy3	SimulationMatrix+1	No attempts yet	1s	128 MB	Judgeable
Recovering the Input NumbersReconstruct the original array that produces the given output when replayed through the circular skip-and-zero traversal.	Easy3	SimulationArray	No attempts yet	1s	32 MB	Judgeable
HunterCount animals within range L of a firing position on the x-axis under distance \|x - a\| + b.	Easy3	Binary searchSorting	No attempts yet	1s	128 MB	Judgeable
Work at a Library Is ToughCount the fewest swaps of out-of-order book pairs that arrange each test case's call numbers in ascending order.	Easy3	Brute forceArray	No attempts yet	1s	128 MB	Judgeable
Rectangle ColoringCount the groups of overlapping rectangles where touching edges count as overlap and each group gets one color.	Easy3	Union-findGeometry	No attempts yet	1s	128 MB	Judgeable
ParenthesesDecide for each parenthesis string of length 2 to 50 whether its brackets match correctly and print YES or NO.	Easy3	Stack	No attempts yet	1s	128 MB	Judgeable
Cross CountryFrom the finishing order, score only six-runner teams by their top four places and pick the lowest total, breaking ties with the fifth runner.	Easy3	SimulationHash map	No attempts yet	1s	128 MB	Judgeable
Goldbach's ConjectureGiven an even number n, print the two primes that sum to n with the smallest gap between them.	Easy3	Number theoryTwo pointers	No attempts yet	2s	256 MB	Judgeable
Iris (Password)Count case-insensitive subsequence occurrences of a word in a text with the prescribed greedy scan and print the count with up to the first three end positions.	Easy3	GreedySimulation+1	No attempts yet	1s	128 MB	Judgeable
FenceScale the given convex polygon to enclose the target area and report the resulting fence length.	Easy3	GeometryMath	No attempts yet	1s	128 MB	Judgeable
The Candy-Sharing GameEach round passes half of each candy pile to the right and tops odd counts to even until every child holds the same number.	Easy3	SimulationArray	No attempts yet	1s	128 MB	Judgeable
6174For each four-digit number, repeat the Kaprekar digit-sort subtraction until 6174 appears and report the step count.	Easy3	SimulationSorting	No attempts yet	1s	128 MB	Judgeable
Coin GameThe program flips full rows, columns, or diagonals of a 3 by 3 coin grid to make all coins match in the fewest moves, or reports -1.	Easy3	Brute forceBit manipulation	No attempts yet	1s	128 MB	Judgeable
Lexicographic rank of a permutationGiven a permutation of the letters a to h, print its 1-based position in lexicographic order.	Easy3	CombinatoricsMath	No attempts yet	1s	128 MB	Judgeable
Primality TestDecide whether each of up to 10 numbers up to 100000000 is prime and print YES or NO.	Easy3	Number theoryMath	No attempts yet	1s	128 MB	Judgeable
Adding 1, 2, and 3Count the ordered ways to write n as a sum of 1, 2, and 3 for each test case with n below 11.	Easy3	Dynamic programming	No attempts yet	1s	512 MB	Judgeable
The SuspectsCount every student connected to student 0 through shared groups, since one suspect makes each joined group suspect.	Easy3	Union-find	No attempts yet	1s	128 MB	Judgeable
Hauling materialCompute the cheapest directed route from the start to the destination for each road network.	Easy3	Shortest pathGraph	No attempts yet	1s	128 MB	Judgeable
Function run funCompute the recursive function w(a, b, c) with memoization for each query line until -1 -1 -1.	Easy3	Dynamic programmingRecursion	No attempts yet	1s	128 MB	Judgeable
Approximate String MatchingFor each word pair, try every offset, keep the largest count of matching letters, and print twice that count over the total length as a reduced fraction.	Easy3	String matchingBrute force+1	No attempts yet	1s	128 MB	Judgeable
Jumble MatchCount how many given words contain a substring that is a rearrangement of the pattern, where underscores match any letter.	Easy3	Sliding windowString+1	No attempts yet	1s	128 MB	Judgeable
Taxi RoutesCount the routes from the southwest to the northeast corner of a grid up to 30 by 30 that move only east or north and avoid blocked intersections.	Easy3	Dynamic programmingMatrix	No attempts yet	1s	128 MB	Judgeable
Inviting the Village ChiefPlant one tree per day in the best order and report the earliest day after all trees have finished growing.	Easy3	GreedySorting	No attempts yet	1s	128 MB	Judgeable
Virus ReplicationGiven the DNA strands before and after one contiguous replacement, find the shortest inserted piece that explains the change.	Easy3	StringTwo pointers	No attempts yet	1s	128 MB	Judgeable
Sudoku GradingCheck each filled 9x9 board and report whether every row, column, and 3x3 box holds the digits 1 to 9 exactly once.	Easy3	ImplementationMatrix	No attempts yet	1s	128 MB	Judgeable
Even More DicePrint every nondecreasing roll of n m-sided dice that sums to s in lexicographic order for each test case.	Easy3	BacktrackingRecursion	No attempts yet	5s	512 MB	Judgeable
Robot in a MazeFind the fewest up, down, left, or right moves from S to any G in each grid maze, or report that no exit exists.	Easy3	BFSMatrix	No attempts yet	1s	128 MB	Judgeable
The real messageDecide whether a received uppercase message could result from duplicating every third occurrence of each letter.	Easy3	SimulationString	No attempts yet	1s	256 MB	Judgeable
Paying Off the DebtSimulate monthly interest rounded to the cent with a fixed payment to count months until the debt clears or report impossible.	Easy3	Simulation	No attempts yet	2s	128 MB	Judgeable
ChromosomeDecide for each uppercase string whether it matches an optional A-to-F letter followed by runs of A, F, and C and an optional closing letter.	Easy3	String matchingString	No attempts yet	2s	64 MB	Judgeable
Fegla and the Bed BugsPlace K bugs on N line cells to maximize the smallest empty gap between neighbors.	Easy3	Binary searchGreedy	No attempts yet	1s	128 MB	Judgeable
FundraisedChoose unlimited units of N item kinds within budget X to maximize total importance.	Easy3	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
It Is ColdFrom the farthest fan inward, add matching flows and subtract opposing ones, resetting on outward flow, to find the speed reaching the team.	Easy3	SimulationArray	No attempts yet	1s	128 MB	Judgeable
EligibilityCount distinct contest years per contestant after dropping duplicate records and print names with four or fewer in lexicographic order.	Easy3	Hash mapSorting	No attempts yet	1s	128 MB	Judgeable
CrankCount the boundary rooftops that can reach the boss by moving only to equal or lower adjacent buildings.	Easy3	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Fashion King HaebinCount all nonempty outfits by picking at most one item from each clothing kind.	Easy3	CombinatoricsHash map	No attempts yet	1s	128 MB	Judgeable
String LDCount how many times the first character can be stripped from every word before a word empties or two words match.	Easy3	StringSimulation+1	No attempts yet	1s	128 MB	Judgeable
A Password Policy RequirementFind the shortest contiguous substring of at least six characters that contains an uppercase letter, a lowercase letter, and a digit.	Easy3	Sliding windowString	No attempts yet	1s	128 MB	Judgeable
Calculate the Fence NeededGiven the coordinates of N unit squares, compute the perimeter of the combined farm shape.	Easy3	Hash mapMath	No attempts yet	1s	128 MB	Judgeable
Largest Pairwise GCDFor each test case, print the largest GCD found among all pairs of the given integers.	Easy3	Number theoryBrute force	No attempts yet	1s	128 MB	Judgeable
Round RobinSimulate rounds of T turns around the circle, remove the player who takes the last turn, and report the survivors and their shared count when the rest tie.	Easy3	Simulation	No attempts yet	1s	128 MB	Judgeable
Sort MeThe program sorts each dataset of up to 20 words by the given custom alphabet and prints the ordered list.	Easy3	SortingString	No attempts yet	1s	128 MB	Judgeable
Ballot Analyzing DeviceCount ballots with exactly one mark as votes, rank candidates by votes keeping ballot order on ties, and print each percentage plus the invalid share.	Easy3	ImplementationSorting+1	No attempts yet	2s	256 MB	Judgeable
Padovan SequenceFor each test case, compute the Nth Padovan number defined by the spiral of equilateral triangles.	Easy3	Dynamic programmingArray	No attempts yet	1s	128 MB	Judgeable
Islands in the Data StreamCount the nested islands, contiguous blocks higher than both neighbors, in each 15-number stream that starts and ends at zero.	Easy3	SimulationStack	No attempts yet	1s	128 MB	Judgeable
Strahler orderGiven a river DAG, compute its Strahler order at node M by processing nodes in topological order.	Easy3	Topological sortGraph	No attempts yet	1s	128 MB	Judgeable
PoliticsOrder supporters by the listed candidate order, keep original order within each candidate, and group unlisted candidates at the end by first appearance.	Easy3	SortingHash map	No attempts yet	15s	256 MB	Judgeable
Generations of TribblesCompute the nth term of a four-term Fibonacci-like recurrence for up to 68 test cases with precomputation.	Easy3	Dynamic programming	No attempts yet	2s	128 MB	Judgeable
LanguagesEach sample line is assigned to the language whose keywords it contains, matched case-insensitively after splitting on spaces and punctuation.	Easy3	Hash mapString	No attempts yet	3s	128 MB	Judgeable
FootballDistribute at most G bought goals across N finished matches to maximize total points, with 3 for a win and 1 for a draw.	Easy3	GreedySorting	No attempts yet	1s	128 MB	Judgeable
Between the MountainsPick one altitude from each mountain so the absolute difference between the two is as small as possible.	Easy3	Two pointersSorting	No attempts yet	1s	128 MB	Judgeable
Goldilocks and the N CowsChoose an integer barn temperature that maximizes total milk when each cow yields X if cold, Y if inside its range, and Z if hot.	Easy3	SortingIntervals	No attempts yet	1s	128 MB	Judgeable
Lucky NumbersCount distinct sums of one element from each of three arrays whose decimal digits are only 5 and 8.	Easy3	Brute forceHash map+1	No attempts yet	1s	128 MB	Judgeable
Equal Sum SetsCount subsets of {1..n} with exactly k elements that sum to s for each dataset.	Easy3	Dynamic programmingCombinatorics	No attempts yet	3s	128 MB	Judgeable
Maximum Word FrequencyCount n lowercase words and print the most frequent word and its count, breaking ties by last lexicographical order.	Easy3	Hash mapString	No attempts yet	1s	128 MB	Judgeable
GCD SumGiven several integers per test case, add the greatest common divisor of every unordered pair and print each sum.	Easy3	Number theoryBrute force	No attempts yet	1s	128 MB	Judgeable
Meeting Room ArrangementPick the largest set of non-overlapping events in each test case from given start and finish times.	Easy3	GreedySorting	No attempts yet	1s	128 MB	Judgeable
BABBAStarting from A and rewriting each B as BA and each A as B, count the As and Bs after K presses.	Easy3	Dynamic programmingMath	No attempts yet	1s	128 MB	Judgeable
Stone GameTwo players alternately take 1 or 3 stones from a pile of N, and the program names the winner under perfect play.	Easy3	Dynamic programmingGame theory	No attempts yet	1s	128 MB	Judgeable
Stone Game 2Two players alternately take 1 or 3 stones from a pile of N and the player taking the last stone loses, so print whether the first player wins.	Easy3	Game theoryDynamic programming	No attempts yet	1s	128 MB	Judgeable
Stone Game 3Two players alternately take 1, 3, or 4 stones from a pile of N, and the program reports whether the first player wins with perfect play.	Easy3	Dynamic programmingGame theory	No attempts yet	1s	128 MB	Judgeable
Stone Game 4Two players alternately take 1, 3, or 4 stones and the player taking the last stone loses; report whether the first player wins with optimal play.	Easy3	Dynamic programmingGame theory	No attempts yet	1s	128 MB	Judgeable
Stone Game 6Two players alternately take 1, 3, or 4 stones from a pile of N, and the program prints which player wins with perfect play.	Easy3	Game theoryDynamic programming	No attempts yet	1s	128 MB	Judgeable
The Original Number of MedallionsGiven the daughter count and the medallions left after the youngest keeps one smallest split share, find the smallest and largest possible original counts.	Easy3	MathBrute force	No attempts yet	1s	128 MB	Judgeable
SifarFor each N up to 1,000,000 given one per line until 0, print the count of trailing zeros of N! as Case #x: M.	Easy3	Number theoryMath	No attempts yet	1s	128 MB	Judgeable
Who you knowFind the cheapest chain of introductions from politician 0 to politician M-1 in an undirected graph with edge weights 1 to 4, printing -1 when unreachable.	Easy3	Shortest pathGraph	No attempts yet	1s	128 MB	Judgeable
The Sultan's ChapatiFollow the prescribed flip procedure to sort each stack largest on the bottom and print the flip positions ending with 0.	Easy3	SimulationArray+1	No attempts yet	1s	128 MB	Judgeable
Rainforest CanopyCount the groups of 1s connected through all eight neighbours in each square binary image.	Easy3	DFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Charles Babbage's Difference EngineGiven the first values of a low-degree polynomial, extend its finite-difference table forward and report the value at x = 50.	Easy3	SimulationMath+1	No attempts yet	1s	128 MB	Judgeable
Surface AreaGiven column heights on a grid, compute the total exposed surface area of the solid, including top, sides, and floor.	Easy3	SimulationMatrix	No attempts yet	1s	128 MB	Judgeable
Bi-coloringCount the two-colorings where every edge joins different colors, or report -1 when the graph is not bipartite.	Easy3	BFSGraph	No attempts yet	1s	128 MB	Judgeable