Problems

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Total results29,304 problems

Infinitely Bursting Bubbles in a Glass Bottle
Medium6
Simulation, Array+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
DevNight Operations
Medium6
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
I Am a Polar Bear
Medium6
Graph, Shortest path+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
I Am a Salmon
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
K-mins
Medium6
Divide and conquer, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Malatang Tanghulu (hard)
Medium6
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
String Erasing Game
Medium6
String, Game theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Comparator
Medium6
Bit manipulation, Matrix+1
No attempts yet
Time limit
3s
Memory limit
2048 MB
Judgeable
Not Another Constructive!
Medium6
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Passport Stamps
Medium6
Greedy, Heap
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Training, Round 2
Medium6
Dynamic programming, Intervals+1
No attempts yet
Time limit
6s
Memory limit
2048 MB
Judgeable
Meeting Place
Medium6
Prefix sum, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fire
Medium6
Intervals, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Choosing Clothes
Medium6
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Problem Made Because Delivery Fees Were Too High
Medium6
Dynamic programming, Bit manipulation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Examination 2
Medium6
String, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Scheming Gardener
Medium6
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Collusion on Two Wheels
Medium6
Binary search, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Find Poly
Medium6
Graph, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Neutral Ground
Medium6
Graph, BFS
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Picking Up the Dice
Medium6
Dynamic programming, Probability+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Restore a Binary Search Tree
Medium6
Sorting, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Plaster Cast Cylinders
Medium6
Implementation, Geometry+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Dandelions
Medium6
Intervals, Simulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Flip Coin Pairs
Medium6
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tree Planting
Medium6
Implementation, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sequence and Queries 45
Medium6
Heap, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
COVID tests
Medium6
Probability, Greedy+1
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Doubled GCD
Medium6
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sharing Bread
Medium6
Math, Combinatorics
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Two Hands, One V
Medium6
Matrix, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Organizing Party
Medium6
Bit manipulation, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Twin Friends
Medium6
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Interstellar Advertising Plan
Medium6
Geometry, Hash map
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Sharing Past Exam Notes
Medium6
Dynamic programming, Probability+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Ones
Medium6
Binary search, Probability+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Aboard the Bus to the Workshop, Hello
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bouquet
Medium6
Dynamic programming, Segment tree
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Prison
Medium6
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cutting Straw Bundles
Medium6
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cheater Search
Medium6
Two pointers, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Survival
Medium6
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Very Strongly Connected Components
Medium6
Geometry, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
A Tree-Filled Tree Problem
Medium6
Intervals, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Coloring the Infinite Plane
Medium6
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Number Game
Medium6
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
n, 3n, 5n
Medium6
Number theory, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Test Drive
Medium6
Simulation, Geometry+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Traces of Binary Search
Medium6
Binary search, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
As expected, my isekai sequence was wrong
Medium6
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The official name of Korea Digital Media High School is too long
Medium6
String, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Voyage
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Master of Permutation Construction
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Rabbit Hole
Medium6
Game theory, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pet Problem Junse
Medium6
Array, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Consecutive Classes Are Tough (Hard)
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Urban Farmer
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Water Tank Job (Easy)
Medium6
Tree, DFS+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Which city is Jinhanju Corporation in?
Medium6
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Finding a B끼B끼 A끼A끼 sequence
Medium6
Graph, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
MatKor Cup Seat Arrangement
Medium6
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Axy+Bx+Cy+D=0
Medium6
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fox Chef
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Machine
Medium6
Bit manipulation, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Divisor Game
Medium6
Number theory, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Base Sorting (Hard)
Medium6
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
ABB to BA (Hard)
Medium6
String, Stack+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sequence and Frog
Medium6
Graph, Shortest path
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mis-generated Data
Medium6
Probability, Tree
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Balanced bracket strings and queries
Medium6
String, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Make an Arithmetic Sequence
Medium6
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Make a Game
Medium6
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tree Craftsman
Medium6
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Complete Patrol
Medium6
Combinatorics, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Want to Become a Tree
Medium6
Tree, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Chocolate Bar Partition
Medium6
Prefix sum, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Make a Number
Medium6
Shortest path, Dynamic programming+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Fix the Tree
Medium6
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Splitting a Histogram into Rectangles
Medium6
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
4-cycle (Hard)
Medium6
Graph, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Battle Royale
Medium6
Simulation, Heap+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Brotherly Harmony
Medium6
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Melody
Medium6
Math, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Card Flipping 1
Medium6
Segment tree, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Steppe on It
Medium6
Tree, Binary search+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Harmonics with Interference
Medium6
Dynamic programming, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Simple Tree Decomposition Problem
Medium6
Tree, Dynamic programming
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Copycat Catcher
Medium6
String matching, String+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Headline Heat
Medium6
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Laundry
Medium6
Math, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
TWINS
Medium6
Binary search, Bit manipulation+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Parentheses
Medium6
Prefix sum, String+1
No attempts yet
Time limit
0.3s
Memory limit
1024 MB
Judgeable
Snake
Medium6
DFS, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Keeping the Tree Healthy
Medium6
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Alien Virus
Medium6
Matrix, Brute force+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Učiteljica
Medium6
Sliding window, Two pointers+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Awkward Auction
Medium6
Dynamic programming, Game theory
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Avoiding the Abyss
Medium6
Geometry, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Infinite Cash
Medium6
Math, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Drone Control
Medium6
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Infinitely Bursting Bubbles in a Glass BottleSimulate bubbles across N zones over T seconds, adding bubbles to a given zone then spreading them up and down, and print the total each second.	Medium6	SimulationArray+1	No attempts yet	3s	1024 MB	Judgeable
DevNight OperationsFor each conference room, find the shortest distance to its second-preferred communication room, where preference is by distance and then by smaller vertex number.	Medium6	Shortest pathGraph+1	No attempts yet	2s	1024 MB	Judgeable
I Am a Polar BearGiven glaciers joined by bridges that collapse at fixed times, find the longest time the bear can stay at glacier 1 and still reach glacier N.	Medium6	GraphShortest path+1	No attempts yet	1.5s	1024 MB	Judgeable
I Am a SalmonEach river accepts salmon whose size lies in its [l, r] range; count the salmon that can swim from village 1 to village N.	Medium6	GraphBFS+2	No attempts yet	2s	1024 MB	Judgeable
K-minsGiven an array of distinct integers, find the sum of the K-th smallest value over every subarray. Subarrays shorter than K contribute 0.	Medium6	Divide and conquerSorting+1	No attempts yet	2s	1024 MB	Judgeable
Malatang Tanghulu (hard)Decide whether inserting P strawberries and Q grapes per minute can equalize every skewer's counts, and output the insert counts if so.	Medium6	Number theoryMath+1	No attempts yet	2s	1024 MB	Judgeable
String Erasing GameGiven a string of 0, 1, and at most one ?, decide whether the first player wins the game of erasing end runs or filling in the ?.	Medium6	StringGame theory+1	No attempts yet	1s	1024 MB	Judgeable
ComparatorGiven a k-bit comparator defined by if-statements over bit pairs, count the words that break reflexivity and the pairs and triples that break symmetry and transitivity.	Medium6	Bit manipulationMatrix+1	No attempts yet	3s	2048 MB	Judgeable
Not Another Constructive!Given a partially filled string of length n up to 40, replace each question mark with an uppercase letter so the string has exactly k subsequences equal to NAC, or report -1.	Medium6	Dynamic programmingString+1	No attempts yet	1s	2048 MB	Judgeable
Passport StampsGiven trips that each need c contiguous blank pages, find the first trip an adversarial officer could block in a passport of p pages.	Medium6	GreedyHeap	No attempts yet	1s	2048 MB	Judgeable
Training, Round 2Given n problems with implementation and thinking skill ranges, find the most problems Ashley can solve in order when each solve raises one of her skills by one.	Medium6	Dynamic programmingIntervals+1	No attempts yet	6s	2048 MB	Judgeable
Meeting PlaceFor each query range [L, R] of house coordinates, the task is to find the minimum fatigue of a meeting set made of the residents in that range.	Medium6	Prefix sumBinary search+1	No attempts yet	1s	1024 MB	Judgeable
FirePick the fewest helper shifts, each inside its [s_i, e_i] window on a repeating M-minute day, so that every minute of the day is covered. Print -1 if impossible.	Medium6	IntervalsGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Choosing ClothesGiven the counts of tops, jeans, sweatpants, light innerwear, and dark innerwear, find the maximum number of days Yura can wear clothes without washing any item.	Medium6	MathGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Problem Made Because Delivery Fees Were Too HighAssign N students to M restaurants so each student's equal share of the fee stays within their limit, minimizing the total fee.	Medium6	Dynamic programmingBit manipulation	No attempts yet	3s	1024 MB	Judgeable
Examination 2Given an IOI function string of threshold atoms joined by !, &, ^, and \| with parentheses, output whether it is True or False for each of Q queried integers.	Medium6	StringBinary search+1	No attempts yet	2s	1024 MB	Judgeable
The Scheming GardenerGiven a planar straight-line graph, find the enclosed plot that an animal from outside must cross the fewest other plots to reach, and maximize that count.	Medium6	GraphBFS+1	No attempts yet	1s	1024 MB	Judgeable
Collusion on Two WheelsSplit N customers into two groups to minimize the largest Manhattan distance between any two customers in the same group.	Medium6	Binary searchGraph+2	No attempts yet	1s	1024 MB	Judgeable
Find PolyGiven line segments as coordinate pairs, count the connected figures among them and how many of those figures are polygons with an Euler trail returning to its start.	Medium6	GraphImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Neutral GroundGiven a grid of A and B troops, costed open squares, and impassable squares, find the minimum total cost of squares to patrol so no A and B squares connect.	Medium6	GraphBFS	No attempts yet	1s	1024 MB	Judgeable
Picking Up the DiceGiven K dice and a first roll, find the smallest number of dice to re-roll that maximizes the chance of reaching the target total T.	Medium6	Dynamic programmingProbability+1	No attempts yet	1s	1024 MB	Judgeable
Restore a Binary Search TreeGiven each node's value and depth, rebuild a binary search tree from them, or report -1 when no such tree exists.	Medium6	SortingDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
Plaster Cast CylindersGiven an R by C grid of cylinder orientations, count the plaster pieces that remain after all cylinders are removed.	Medium6	ImplementationGeometry+1	No attempts yet	4s	1024 MB	Judgeable
DandelionsGiven daily wind (L, R), planting (C x), and query (Q) commands on an infinite row of pots, print the count of occupied pots at each Q.	Medium6	IntervalsSimulation+1	No attempts yet	2s	1024 MB	Judgeable
Flip Coin PairsGiven a row of N coins marked H or T, find the fewest operations that flip two adjacent equal coins to make every coin heads, or report -1 if impossible.	Medium6	StringGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Tree PlantingDecide if a connected set of grid cells exists with A cells of even neighbor count and B of odd, and print one layout.	Medium6	ImplementationMath	No attempts yet	2s	1024 MB	Judgeable
Sequence and Queries 45Process q queries that add \|i-x\|+y to every element of a huge array, and report the first index of the minimum and its value for each type 2 query.	Medium6	HeapMath+1	No attempts yet	1s	1024 MB	Judgeable
COVID testsFind every positive sample among N saliva samples, where each is positive with probability P, using as few mixed antigen tests as possible.	Medium6	ProbabilityGreedy+1	No attempts yet	Not set	1024 MB	Judgeable
Doubled GCDGiven N numbers, repeatedly replace two cards x and y with 2 * gcd(x, y) until one card is left, and find the largest possible final value.	Medium6	Number theoryMath+1	No attempts yet	2s	1024 MB	Judgeable
Sharing BreadCount the starting sequences of M people over N toasters where every person finds a piece of bread, modulo 998244353.	Medium6	MathCombinatorics	No attempts yet	2s	1024 MB	Judgeable
Two Hands, One VGiven a binary grid, find the maximum number of blue cells after two V-shaped paintings, each following an upper-left and upper-right diagonal from a white cell.	Medium6	MatrixDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Organizing PartyUsing at most 7 queries, each returning the guests acquainted with any guest in a chosen set, find one guest who has zero or more than one acquaintance.	Medium6	Bit manipulationImplementation	No attempts yet	2s	1024 MB	Judgeable
Twin FriendsCount pairs of a permutation A' of A and a length-N string B' from B, where each B' letter equals or follows the matching A' letter, modulo 998244353.	Medium6	CombinatoricsDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Interstellar Advertising PlanCount the rectangles with positive area whose four vertices are among N stars in 3D space, for each dataset.	Medium6	GeometryHash map	No attempts yet	8s	1024 MB	Judgeable
Sharing Past Exam NotesFind the expected number of subjects student 1 holds after K random edge-sharing events on a friendship graph, modulo 998244353.	Medium6	Dynamic programmingProbability+1	No attempts yet	8s	1024 MB	Judgeable
OnesFind the positions of all k ones in a random n-bit sequence using range queries that only ask whether a segment contains a 1, minimizing the query count.	Medium6	Binary searchProbability+1	No attempts yet	1s	1024 MB	Judgeable
Aboard the Bus to the Workshop, HelloGiven a 3-row by N-column bus with staff seats in rows 1 and 3, find the fewest air conditioners to turn on so every cell is cooled, or -1 if impossible.	Medium6	Dynamic programmingGreedy	No attempts yet	1s	1024 MB	Judgeable
BouquetGiven N tulips with left and right protection ranges, find the largest set of tulips where no picked tulip falls inside another picked tulip's protected range.	Medium6	Dynamic programmingSegment tree	No attempts yet	3s	1024 MB	Judgeable
PrisonGiven a star-shaped polygon around the origin and a chain of prisoner moves, report for each prisoner whether they end inside the guard's view.	Medium6	GeometryBinary search+1	No attempts yet	1s	1024 MB	Judgeable
Cutting Straw BundlesChoose a straight cutting line across N straws of height H so the total quadrilateral area is at least S, minimizing the sum of f_i times each straw's area.	Medium6	MathGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Cheater SearchFind a contiguous cheater interval [l, r] so that cheaters' claimed ranges avoid it and every non-cheater's claimed range overlaps it.	Medium6	Two pointersPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
SurvivalEach point links to its nearest point (ties go to the larger index). Find the most sides of a simple polygon formed by these links, or -1 if none exists.	Medium6	GeometryMath+1	No attempts yet	1s	1024 MB	Judgeable
Very Strongly Connected ComponentsGiven N distinct integer points, find the maximum number of line segments you can draw between them so that segments meet only at endpoints.	Medium6	GeometrySorting	No attempts yet	1s	1024 MB	Judgeable
A Tree-Filled Tree ProblemGiven N lecture time intervals, find for each query the maximum number of non-overlapping lectures that includes the query's mandatory lectures.	Medium6	IntervalsGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Coloring the Infinite PlaneGiven N integer vectors, find the density of the lattice they generate in the plane, printed as a fraction modulo 1,000,000,007.	Medium6	MathNumber theory	No attempts yet	2s	1024 MB	Judgeable
Number GameGiven 1 to N on a board, repeatedly replace two numbers with their absolute difference. Maximize the final number and print the operations.	Medium6	MathGreedy+1	No attempts yet	2s	1024 MB	Judgeable
n, 3n, 5nFor each query i, find the i-th term of the lexicographically smallest increasing sequence where each positive integer n has exactly one of n, 3n, and 5n in the sequence.	Medium6	Number theoryGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Test DriveGiven a one-way triangle with lane counts per road and two cars that cannot pass when lanes are full, print each car's lap time.	Medium6	SimulationGeometry+1	No attempts yet	2s	1024 MB	Judgeable
Traces of Binary SearchGiven N and a binary search trace of probed values, count the strictly increasing arrays with values from 1 to 100 that produce that exact trace, modulo 10^9+7.	Medium6	Binary searchDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
As expected, my isekai sequence was wrongFind the minimum number of +K and +1 operations needed to make the sequence a palindrome, where each operation raises one element.	Medium6	MathGreedy	No attempts yet	1s	1024 MB	Judgeable
The official name of Korea Digital Media High School is too longSplit string S into a prefix and suffix to maximize min(\|A\|, \|B\|) minus the length of their longest common substring.	Medium6	StringDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
VoyageGiven N sandwiches, cut meals of length X to Y cm from them to maximize the meal count, then minimize the total length of discarded remainders.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Master of Permutation ConstructionCount permutations P of length N (up to 5000) so that B = (A_P1, ..., A_PN) has at most K strict left-to-right maxima, modulo 1,000,000,007.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Rabbit HoleTwo players alternately empty part of one rabbit hole or merge two holes into their XOR, and the one who makes the last move wins. Decide who wins with optimal play.	Medium6	Game theoryBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Pet Problem JunseEach element is replaced by the count of later elements greater than it. Find how many rounds until the array stops changing, or -1 if it never does.	Medium6	ArraySimulation	No attempts yet	1s	1024 MB	Judgeable
Consecutive Classes Are Tough (Hard)Given n periods where some classes are required, count the 0/1 timetables whose longest run of consecutive classes is exactly k, modulo 1e9+7.	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Urban FarmerGiven n lettuces with sizes below m, find the fewest nutrient uses (A, B, or C) so that every lettuce reaches size m or more.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Water Tank Job (Easy)Given a binary tree of water tanks with capacities, pick one tank to pour m units into and find the maximum number of tanks that end up full.	Medium6	TreeDFS+1	No attempts yet	3s	1024 MB	Judgeable
Which city is Jinhanju Corporation in?Given the three distances between capitals of a triangle, find the area shared by three circles, each centered at a capital with radius equal to the opposite distance.	Medium6	GeometryMath	No attempts yet	1s	1024 MB	Judgeable
Finding a B끼B끼 A끼A끼 sequenceGiven A, B, and N, build a sequence that uses each pair (x, y) with y - x equal to A or B exactly once as an adjacent pair, or print -1 if none exists.	Medium6	GraphImplementation	No attempts yet	1s	1024 MB	Judgeable
MatKor Cup Seat ArrangementGiven N participants and M seats, find for each i from 0 to N the probability that exactly i participants are predicted to sit in their assigned seat.	Medium6	CombinatoricsMath	No attempts yet	2s	1024 MB	Judgeable
Axy+Bx+Cy+D=0Given integers A, B, C, D, list every integer pair (x, y) satisfying Axy+Bx+Cy+D=0, or print INFINITY if there are infinitely many.	Medium6	MathNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Fox ChefGiven a row of O and X cookies, find the fewest flips of at least K consecutive cookies that make all cookies show the same side, and list those flips.	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
MachineRecover the hidden permutation P by querying a machine that returns A[P[i]] XOR X for an unknown X, within a limit on the number of queries.	Medium6	Bit manipulationArray+1	No attempts yet	1s	1024 MB	Judgeable
Divisor GameFor each quiz (x, A, B, C), count y in 1 to N with \|x-y\| at most A, \|D(x)-D(y)\| at most B, and \|S(x)-S(y)\| at most C, where D and S are the divisor count and divisor sum.	Medium6	Number theorySegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Base Sorting (Hard)Find the 0-based rank of a base-M string of length N when all such strings are sorted by digit counts from M-1 down to 0, then by reversed value.	Medium6	CombinatoricsMath+1	No attempts yet	1s	1024 MB	Judgeable
ABB to BA (Hard)Repeatedly replace the leftmost ABB in a string of A and B with BA until none remains, then print the final string.	Medium6	StringStack+1	No attempts yet	2s	1024 MB	Judgeable
Sequence and FrogGiven arrays a and b, a frog starts at x, jumps to x-a_x or x+a_x after waiting b_x seconds each step. Find the earliest time it can leave the array for every start.	Medium6	GraphShortest path	No attempts yet	2s	1024 MB	Judgeable
Mis-generated DataClassify each of 1000 permutations of length 1000 as coming from a uniform random BST-insertion generator or a biased variant, with at least 900 correct.	Medium6	ProbabilityTree	No attempts yet	5s	1024 MB	Judgeable
Balanced bracket strings and queriesPoint updates change characters in a string of '(', ')', and '*', and range queries ask whether the stars in a substring can be filled to form a balanced bracket string.	Medium6	StringSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Make an Arithmetic SequenceGiven N and M, find N non-prime positive integers up to 2,000,000 that form an arithmetic sequence with common difference M, or print -1 if none exists.	Medium6	Number theoryMath+1	No attempts yet	1s	1024 MB	Judgeable
Make a GamePlayers alternately extend a path that never revisits a cell, starting from the center of an odd N x N grid, and the player who moves onto the border wins. Find the winner.	Medium6	Game theoryMath	No attempts yet	1s	1024 MB	Judgeable
Tree CraftsmanGiven a simple graph, count the ways to add edges so it becomes a tree, or report -1 if that count exceeds K.	Medium6	GraphUnion-find+1	No attempts yet	1s	1024 MB	Judgeable
Complete PatrolCount the ways to split every road into closed patrol routes that each use a road at most once, modulo 1000000007.	Medium6	CombinatoricsGraph	No attempts yet	2s	1024 MB	Judgeable
Want to Become a TreeGiven a set of nodes in the infinite binary tree rooted at 1, count the nodes that have no ancestor in the set, or print -1 if there are infinitely many.	Medium6	TreeBit manipulation+1	No attempts yet	1s	1024 MB	Judgeable
Chocolate Bar PartitionSplit a 2 x N grid of tastiness values into the largest number of connected parts that all have the same mean.	Medium6	Prefix sumHash map+1	No attempts yet	1s	1024 MB	Judgeable
Make a NumberFind the minimum cost to turn A into B using single-digit changes (cost is the digit gap) or adding an integer y (cost \|y\|).	Medium6	Shortest pathDynamic programming+1	No attempts yet	1.5s	1024 MB	Judgeable
Fix the TreeGiven a tree with some broken vertices, repair at most K of them to maximize the number of vertices that still work, where a vertex works only if no ancestor is broken.	Medium6	TreeDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Splitting a Histogram into RectanglesGiven N adjacent rectangles with widths and heights, find the minimum total length of cuts that split the histogram into rectangles.	Medium6	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
4-cycle (Hard)Count the distinct simple cycles of length 4 in an undirected graph with up to 10^5 vertices and edges, output modulo 10^9+7.	Medium6	GraphCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Battle RoyaleGiven each player's attack power and health, find the number of the last player alive when players attack in cyclic turn order.	Medium6	SimulationHeap+1	No attempts yet	1s	1024 MB	Judgeable
Brotherly HarmonyTwo brothers swap and merge bundle pairs from paddy i into paddy j (i<j) until all bundles sit in paddy N. Find the maximum absolute difference between the two N-th paddies.	Medium6	GreedyMath	No attempts yet	1s	1024 MB	Judgeable
MelodyGiven counts a_1 to a_N for notes 1 to N, decide whether a sequence starting at note 1 can visit each note a_i times, moving to an adjacent note at each step.	Medium6	MathGraph+1	No attempts yet	1s	1024 MB	Judgeable
Card Flipping 1Given N cards with fronts p_1 to p_N, flip card j whenever an earlier card's top exceeds its top, then output each card's final top.	Medium6	Segment treeMath	No attempts yet	2s	1024 MB	Judgeable
Steppe on ItPlace f fire stations on a weighted tree of n villages to minimize the largest distance from any village to its nearest station.	Medium6	TreeBinary search+1	No attempts yet	3s	1024 MB	Judgeable
Harmonics with InterferenceFill the * bits of M' and N' with 0 or 1 so that the binary value of M is divisible by the binary value of N.	Medium6	Dynamic programmingNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Simple Tree Decomposition ProblemCount the edge subsets of a tree whose removal leaves every connected component with exactly A or B vertices, modulo 10^9+7.	Medium6	TreeDynamic programming	No attempts yet	3s	1024 MB	Judgeable
Copycat CatcherFor each query, checks whether it matches a contiguous run of reference tokens after a consistent one-to-one renaming of single-letter variables.	Medium6	String matchingString+1	No attempts yet	3s	1024 MB	Judgeable
Headline HeatGiven university names, rival pairs, and news articles, decide for each article whether some university is mentioned fewer times than one of its rivals.	Medium6	String matchingString+1	No attempts yet	2s	1024 MB	Judgeable
LaundryGiven seven pile sizes for the programme combinations and a load capacity k, find the minimum number of loads, where each load uses one of programmes A, B, or C.	Medium6	MathGreedy	No attempts yet	2s	1024 MB	Judgeable
TWINSFind the one or two Reni pictures among N by asking group queries that check whether a set contains any Reni picture, using few groups and questions.	Medium6	Binary searchBit manipulation+1	No attempts yet	0.5s	1024 MB	Judgeable
ParenthesesFor many queries, find the minimum number of swaps that turns a balanced substring of a bracket sequence into a regular bracket sequence.	Medium6	Prefix sumString+1	No attempts yet	0.3s	1024 MB	Judgeable
SnakeGiven a grid with a snake of up to 16 cells and one apple, decide whether the snake's head can reach the apple without hitting a wall or its own body.	Medium6	DFSHash map+1	No attempts yet	2s	1024 MB	Judgeable
Keeping the Tree HealthyGiven a tree whose nodes are marked 1 (unhealthy) or 0, cut the fewest edges so every connected component has at most K unhealthy nodes, and print that count.	Medium6	TreeDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Alien VirusGiven a grid of 0s and 1s, find the largest axis-aligned right isosceles triangle whose boundary cells all contain 1, measured by the cell count of one leg.	Medium6	MatrixBrute force+1	No attempts yet	2s	1024 MB	Judgeable
UčiteljicaCount the ways to delete some prefix and suffix so that, for each i from 1 to K (K at most 4), some value appears exactly i times in what remains.	Medium6	Sliding windowTwo pointers+2	No attempts yet	5s	1024 MB	Judgeable
Awkward AuctionGiven n and bribe b, find the worst-case total cost of bidding to hit a hidden integer value from 1 to n, when each low bid costs b and each bid is paid.	Medium6	Dynamic programmingGame theory	No attempts yet	1s	1024 MB	Judgeable
Avoiding the AbyssFind up to 10 waypoints for a polyline from start to target that avoids an unknown axis-aligned rectangle known to contain a given point.	Medium6	GeometryImplementation	No attempts yet	1s	1024 MB	Judgeable
Infinite CashGiven a salary s, a pay interval d, and starting cash m, all in binary up to 2^1000, find the first day Svalur has no money to spend, or report infinite money.	Medium6	MathBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Drone ControlGiven pitch, roll, and yaw targets, find four flap angles that produce them while minimizing the largest absolute flap angle.	Medium6	MathImplementation	No attempts yet	2s	1024 MB	Judgeable