Interview core

Mediums from real onsites

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Total results3,617 problems

Portal Gun
Medium5
Sorting, Prefix sum
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Escape from Asgard
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Harmonic Series Modulo a Prime
Medium5
Number theory, Math+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Budget
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
An Interesting Puzzle
Medium5
Minimum spanning tree, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Eastern Express Cars
Medium5
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Hard Problem
Medium5
String, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Not so rough
Medium5
Sliding window, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Waffle
Medium5
String matching, Prefix sum
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Landscape Design
Medium5
Sorting, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Big Round Table
Medium5
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Operation Permutation
Medium5
Topological sort, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Library
Medium5
Greedy, Heap+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
For Collectivism!
Medium5
Sorting, Sliding window+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Secret Rooms
Medium5
Graph, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Megazords
Medium5
Hash map, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Railway Crossing
Medium5
Intervals, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sweet Life
Medium5
Game theory, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Championship
Medium5
Greedy, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Minimal Period
Medium5
String, String matching
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Weapon choice
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Kevin's Swap Trap
Medium5
Sorting, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Kevin and the Remote Car
Medium5
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cipher Message
Medium5
Math, Binary search
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Jumping on Stones
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pencils
Medium5
Sorting, Sliding window
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Game
Medium5
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Domino Game
Medium5
Dynamic programming, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Graph
Medium5
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Little Mischief
Medium5
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Problem for Alf
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gym
Medium5
Hash map, Math
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Physical Education Class
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cipher
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pastries
Medium5
Greedy, Heap+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Giant Jumps
Medium5
Greedy, Heap
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Table
Medium5
Greedy, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Archery Duel
Medium5
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Attack
Medium5
BFS, Simulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cold-blooded Oak
Medium5
Tree, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Stenka na stenku
Medium5
Greedy, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Völund
Medium5
Greedy, Intervals+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hel
Medium5
Segment tree, Array+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Assault
Medium5
Matrix, BFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Treasures
Medium5
Sliding window, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Assault
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
We Are Meat! We Are Gas!
Medium5
Array, Segment tree
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Metro
Medium5
Union-find, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Coloring
Medium5
Binary search, Implementation+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Garnett's House
Medium5
Matrix, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Crime Scene
Medium5
Sliding window, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Crystals
Medium5
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Drawing
Medium5
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Code Lock
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Harry Potter and the Hall of Prophecy
Medium5
Sorting, Heap+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Symmetric Clearing
Medium5
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bickford Fuse
Medium5
Shortest path, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cake
Medium5
Geometry, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fibonacci Subsequence
Medium5
Hash map, Simulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candies
Medium5
Sorting, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bunkers
Medium5
Tree, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Interesting Numbers
Medium5
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Magic Mushrooms
Medium5
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
SMS
Medium5
Sorting, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Flight Connection
Medium5
Sorting, Two pointers
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Business Meetings
Medium5
Dynamic programming, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cylon Code
Medium5
Dynamic programming, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Base String
Medium5
String, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Splitting the Army into Three Squads
Medium5
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Smooth numbers
Medium5
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Delivery
Medium5
Dynamic programming, Prefix sum
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Healthy Diet
Medium5
Sliding window, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Beautiful Numbers
Medium5
Binary search, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Combination Lock
Medium5
Greedy, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fibonacci Strings 2
Medium5
Divide and conquer, Recursion+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Permutation Problem
Medium5
Combinatorics, Backtracking
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Lottery
Medium5
Math, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Figure Skating
Medium5
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Enigmatic Number
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sign Flip Table
Medium5
Matrix, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Trams
Medium5
Tree, DFS+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Islands
Medium5
Graph, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Oil Mining
Medium5
Matrix, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Role-Playing Game
Medium5
Dynamic programming, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
How Many Stars Are in the Sky?
Medium5
Sorting, Prefix sum+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Tampered Records
Medium5
Dynamic programming, Binary search
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Bushil, the King of Short Coding
Medium5
Array, Sliding window
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
A Plus B
Medium5
Heap, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lazdynas
Medium5
Greedy, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Untie
Medium5
Dynamic programming, String
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Intruder Outsmarting
Medium5
Number theory, Math+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Railroad Maintenance
Medium5
Graph, DFS
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Game Sort: Part 1
Medium5
String, Greedy
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Traitor
Medium5
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Doing Assignments Efficiently
Medium5
Dynamic programming, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two Pointers (easy version)
Medium5
Sorting, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Love Letter
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Folders
Medium5
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Domino Stones
Medium5
Graph, BFS
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Word Groups
Medium5
Bit manipulation, Brute force+1
No attempts yet
Time limit
0.1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Portal GunGiven two arrays A and B of n values each, compute the sum over all index pairs (i, j) of (i - j) times \|a_i - b_j\|.	Medium5	SortingPrefix sum	No attempts yet	2s	1024 MB	Judgeable
Escape from AsgardSplit groups of people between an upper deck with A seats and a lower deck with B seats, and check whether group 1 can sit on the upper deck.	Medium5	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
Harmonic Series Modulo a PrimeGiven a prime p and a range l to r, compute the sum of the modular inverses of each i in the range, modulo p.	Medium5	Number theoryMath+1	No attempts yet	4s	1024 MB	Judgeable
BudgetAssign each of n amounts as income or expense so the running balance stays within [a, b] after every operation, or report Impossible.	Medium5	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
An Interesting PuzzleGiven n integer points, split them into two non-empty sets to maximize the minimum distance across the sets, and output that distance squared.	Medium5	Minimum spanning treeGraph	No attempts yet	2s	1024 MB	Judgeable
Eastern Express CarsGiven passenger counts in n cars, find the minimum time to unload everyone when one step empties a car or removes one passenger from each nonempty car.	Medium5	GreedySorting	No attempts yet	2s	1024 MB	Judgeable
A Hard ProblemGiven two binary sequences, find the length of the longest common subsequence that is non-decreasing.	Medium5	StringPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Not so roughGiven a lowercase string and a limit c, find the length of the longest substring with at most c pairs where an 'a' comes before a 'b'.	Medium5	Sliding windowString	No attempts yet	2s	1024 MB	Judgeable
WaffleCount the windows of length m*(a+b) in a 0/1 chocolate string that can be trimmed into a waffle with a chocolate squares, then b blank squares, repeated m times.	Medium5	String matchingPrefix sum	No attempts yet	2s	1024 MB	Judgeable
Landscape DesignGiven n column heights and a step k, find the fewest unit changes so the heights repeat every two columns and adjacent columns differ by exactly k.	Medium5	SortingGreedy	No attempts yet	2s	1024 MB	Judgeable
Big Round TableMasha swaps with a neighbor on a round table of n seats exactly k times; the task is to count the seats where she can end up.	Medium5	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Operation PermutationFind the smallest number of reported pairs after which the order of soldiers is uniquely determined, or -1 if it never becomes unique.	Medium5	Topological sortGraph+1	No attempts yet	1s	1024 MB	Judgeable
LibraryGiven n books with borrow day, deadline, and reading time, decide whether one book per day can be returned on time for all of them.	Medium5	GreedyHeap+1	No attempts yet	2s	1024 MB	Judgeable
For Collectivism!Pick the largest set of assistants whose counts can all be reduced to one common value using at most k creatures in total, then list the rest.	Medium5	SortingSliding window+1	No attempts yet	2s	1024 MB	Judgeable
Secret RoomsChange the exit of one room so that starting from room 1, the exits form a single cycle through all n rooms, or report that it is impossible.	Medium5	GraphArray+1	No attempts yet	2s	1024 MB	Judgeable
MegazordsCount the ways to pick one green, one red, and one blue zord whose boundary digits match and whose three model numbers are all different.	Medium5	Hash mapMath+1	No attempts yet	2s	1024 MB	Judgeable
Railway CrossingGiven moving train segments and car arrival times, find for each car the earliest moment the crossing at x is free.	Medium5	IntervalsSorting+1	No attempts yet	2s	1024 MB	Judgeable
Sweet LifeTwo players take up to k candies per turn, never the same count as the opponent's last move; find who wins from n candies with Masya moving first.	Medium5	Game theoryMath	No attempts yet	2s	1024 MB	Judgeable
ChampionshipGiven each monster's count of acquaintances on the other team, build a bipartite acquaintance graph that meets every count, or report NO if none exists.	Medium5	GreedyGraph	No attempts yet	2s	1024 MB	Judgeable
Minimal PeriodGiven a string with one extra character inserted, find the shortest original block that repeats and then ends in a prefix of itself.	Medium5	StringString matching	No attempts yet	6s	1024 MB	Judgeable
Weapon choiceAssign each of n soldiers to automatic or throwing weapons to maximize total efficiency, while the two group sizes differ by at most m.	Medium5	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
Kevin's Swap TrapGiven n board weights, find two boards whose total weight is at most x and whose weights differ by at least y, or report 0.	Medium5	SortingTwo pointers+1	No attempts yet	2s	1024 MB	Judgeable
Kevin and the Remote CarGiven two digit strings, decide whether the first can be reduced to the second by repeatedly replacing adjacent digits with their sum modulo 10.	Medium5	GreedyString+1	No attempts yet	2s	1024 MB	Judgeable
Cipher MessageCount the natural numbers whose every digit lies within positions l to r of the string formed by concatenating 1, 2, 3, and so on.	Medium5	MathBinary search	No attempts yet	2s	1024 MB	Judgeable
Jumping on StonesFind the fewest 1 or 2 meter jumps from point 0 to point n that land only on stones, and print the lexicographically smallest jump sequence.	Medium5	Dynamic programmingArray+1	No attempts yet	2s	1024 MB	Judgeable
PencilsPick k of n pencil sets so that the gap between the longest and shortest pencil in the combined box is as small as possible.	Medium5	SortingSliding window	No attempts yet	2s	1024 MB	Judgeable
GameJaime and Cersei take turns subtracting 1 from a suffix of a sorted distinct array, and whoever creates a duplicate or a zero loses. Find the winner.	Medium5	Game theoryMath	No attempts yet	1s	1024 MB	Judgeable
Domino GameGiven n dominoes (a, b) with b at most a, find the length of the longest chain where each domino's b matches the next domino's a, without rotating.	Medium5	Dynamic programmingGraph+1	No attempts yet	2s	1024 MB	Judgeable
GraphCount non-adjacent vertex pairs where adding an edge creates exactly one simple cycle, meaning the path between them is unique.	Medium5	GraphDFS+1	No attempts yet	2s	1024 MB	Judgeable
Little MischiefGiven a weighted graph as an adjacency matrix, find the largest number of vertices whose shortest distance from vertex 1 changes after removing one edge.	Medium5	GraphShortest path+1	No attempts yet	2s	1024 MB	Judgeable
A Problem for AlfArrange the given non-negative integers in an order so that concatenating them produces the largest possible number.	Medium5	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
GymCount the pairs of distinct points whose squared Euclidean distance equals d, given n points with integer coordinates.	Medium5	Hash mapMath	No attempts yet	3s	1024 MB	Judgeable
Physical Education ClassCount the ways to split a row of n numbers into contiguous groups, each non-decreasing or non-increasing, modulo 1e9+7.	Medium5	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
CipherCount the original binary strings whose run-length encoding (each run's character followed by its decimal length) equals the given binary string, modulo 1e9+7.	Medium5	Dynamic programmingString+1	No attempts yet	2s	1024 MB	Judgeable
PastriesFind the maximum number of pastries Scrooge can eat within T seconds, starting at coordinate 0 on a line where each pastry at x_i takes t_i to eat.	Medium5	GreedyHeap+1	No attempts yet	2s	1024 MB	Judgeable
Giant JumpsGiven n jumps with lengths a_i and thresholds t_i, find the minimum total training hours over all orders of the jumps.	Medium5	GreedyHeap	No attempts yet	2s	1024 MB	Judgeable
TableFind an order of the k columns that sorts the n rows lexicographically in ascending order, or report -1 if no such order exists.	Medium5	GreedyArray	No attempts yet	2s	1024 MB	Judgeable
Archery DuelTwo players alternately shoot a chained target or resign, and the task is to print the first player's score under optimal play.	Medium5	Game theoryDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
AttackGiven a road network and the vampire clan in each city, decide whether the defenders of the attacked city can hold out against a werewolf army that loses min(t, a, b) per day.	Medium5	BFSSimulation+1	No attempts yet	2s	1024 MB	Judgeable
Cold-blooded OakGiven a rooted tree with bulb counts on vertices, support adding and removing bulbs and answer f(x), the total wire count over all edges in the subtree of x.	Medium5	TreePrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Stenka na stenkuSplit k opponents into consecutive segments so each fighter i takes between a_i and b_i of them, or report FAIL when that is impossible.	Medium5	GreedyImplementation	No attempts yet	2s	1024 MB	Judgeable
VölundEach day, at most m forges can be used by the smiths available that day. Find the maximum number of rings and the minimum total wage.	Medium5	GreedyIntervals+1	No attempts yet	2s	1024 MB	Judgeable
HelGiven an array with point updates, find for each range the largest pain gained by multiplying exactly one element in the range by k.	Medium5	Segment treeArray+1	No attempts yet	4s	1024 MB	Judgeable
AssaultCount the cells of an n by m grid whose pirate count is strictly greater than that of every side-adjacent cell.	Medium5	MatrixBFS	No attempts yet	2s	1024 MB	Judgeable
TreasuresGiven n piles generated by a recurrence, find the shortest consecutive block whose sum is at least the sum of all other piles.	Medium5	Sliding windowTwo pointers+1	No attempts yet	2s	32 MB	Judgeable
AssaultPick bunkers whose closing times strictly increase so the total Decepticons killed is maximized, then output the chosen bunker numbers.	Medium5	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
We Are Meat! We Are Gas!Count pairs of even-height players where the taller one stands left of the shorter one and at least one odd-height player stands between them.	Medium5	ArraySegment tree	No attempts yet	2s	1024 MB	Judgeable
MetroFor each train type, count the connected groups of stations linked by segments of that type, since one train covers each group.	Medium5	Union-findGraph	No attempts yet	2s	1024 MB	Judgeable
ColoringEach step adds a rectangle anchored at (1,1), and the task is to print the area of the union of all rectangles after every step.	Medium5	Binary searchImplementation+1	No attempts yet	1.5s	1024 MB	Judgeable
Garnett's HouseGiven an n by m grid with two marked cells, find the largest axis-aligned subrectangle that contains exactly one of them.	Medium5	MatrixGreedy	No attempts yet	1s	1024 MB	Judgeable
Crime SceneGiven a convex polygon with some fence sides missing, find the minimum total length of missing sides that a tape of length l walked along the boundary cannot cover.	Medium5	Sliding windowTwo pointers+2	No attempts yet	2s	1024 MB	Judgeable
CrystalsChoose a nonempty multiset of crystal types, reusing allowed, so that the sum of (a_i minus b_i) over the picks is zero, using at most 10,000 picks.	Medium5	MathGreedy+1	No attempts yet	2s	1024 MB	Judgeable
DrawingGiven a chain of segments with fixed lengths anchored at A0, decide whether its end can reach point An, and output every hinge position if so.	Medium5	GeometryMath+1	No attempts yet	2s	1024 MB	Judgeable
Code LockGiven n displays where pressing button i copies display i+1 into display i, find the fewest presses that make the sequence non-decreasing.	Medium5	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
Harry Potter and the Hall of ProphecyRepeatedly pick the closest remaining pair of 2n potions (ties go to the larger sum) and print the stronger of each pair for Neville and the weaker for Harry.	Medium5	SortingHeap+2	No attempts yet	2s	1024 MB	Judgeable
Symmetric ClearingGiven n trees around a circle, each birch or pine, decide whether some line through the center reflects the circle onto itself.	Medium5	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Bickford FuseGiven a graph of knots and ropes with burn times, find the knot whose lighting lets the whole fuse burn out in the least time, and report that time.	Medium5	Shortest pathGraph	No attempts yet	2s	1024 MB	Judgeable
CakeDecide whether two perpendicular lines through the center can split the round cake into four pieces, each holding exactly one candle, with no line touching a candle.	Medium5	GeometrySorting	No attempts yet	2s	1024 MB	Judgeable
Fibonacci SubsequenceDecide whether the given n numbers can be rearranged into a sequence where each term is the sum of the two before it.	Medium5	Hash mapSimulation+1	No attempts yet	2s	1024 MB	Judgeable
CandiesEach guest takes one candy from every box holding at least their boldness; output how many candies each guest eats.	Medium5	SortingTwo pointers+1	No attempts yet	2s	1024 MB	Judgeable
BunkersGiven a tree of n nodes, decide whether one vertex has degree 2 and its two branches are equal-sized mirror images.	Medium5	TreeHash map+1	No attempts yet	2s	1024 MB	Judgeable
Interesting NumbersCount the integers from a to b that contain at least k identical digits in a row, with b up to 4 * 10^18 and k up to 20.	Medium5	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
Magic MushroomsFor each of N numbers, print Yes if it is a Fibonacci number (1, 1, 2, 3, 5, ...) and No otherwise.	Medium5	MathNumber theory	No attempts yet	2s	1024 MB	Judgeable
SMSGiven how often each of n letters is typed and m buttons, assign the letters to buttons so the total number of presses is minimal.	Medium5	SortingDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Flight ConnectionPick the cheapest pair of flights, A to the capital and capital to B, with at least 15 minutes between landing and departure, earliest arrival in B on ties.	Medium5	SortingTwo pointers	No attempts yet	2s	1024 MB	Judgeable
Business MeetingsFind the largest set of meetings Alexei can attend in some order, given each meeting's allowed mood range and mood change, starting from mood k.	Medium5	Dynamic programmingBit manipulation	No attempts yet	2s	1024 MB	Judgeable
Cylon CodeGiven an n by m matrix A encoded with a 2x2 matrix C (entries at most 1 in absolute value, C22 nonzero), recover the original matrix B.	Medium5	Dynamic programmingImplementation	No attempts yet	2s	1024 MB	Judgeable
Base StringGiven strings s and t, find the longest string q such that both s and t are repetitions of q, or report <<NO>> if none exists.	Medium5	StringNumber theory	No attempts yet	2s	1024 MB	Judgeable
Splitting the Army into Three SquadsCount the ways to split n warriors into three squads: a power of 3, a multiple of 13 (possibly 0), and a size in [a, b].	Medium5	MathNumber theory	No attempts yet	2s	1024 MB	Judgeable
Smooth numbersGiven a digit count l (1 to 100), find the largest l-digit number whose interior digits are each less than the average of their neighbors, or report -1.	Medium5	MathGreedy+1	No attempts yet	2s	1024 MB	Judgeable
DeliverySplit N houses on a road between two couriers, one starting at the left end and one at the right, to minimize the total toll they pay.	Medium5	Dynamic programmingPrefix sum	No attempts yet	2s	1024 MB	Judgeable
Healthy DietGiven m daily bun prices and a shelf life of k days, find the minimum cost of 2 buns per morning and how many buns to buy each day.	Medium5	Sliding windowGreedy	No attempts yet	2s	1024 MB	Judgeable
Beautiful NumbersGiven n and a set of k digits, find the n-th non-negative integer in increasing order whose leading digit is one of the chosen digits.	Medium5	Binary searchMath	No attempts yet	2s	1024 MB	Judgeable
Combination LockGiven an n-digit number m in base k, find the smallest larger n-digit number in base k with the same digit sum, or report that none exists.	Medium5	GreedyMath	No attempts yet	2s	1024 MB	Judgeable
Fibonacci Strings 2For each test case, count the letter a among the first k characters of the Fibonacci string F_n, where F_0 is a, F_1 is b, and F_i is F_(i-2) followed by F_(i-1).	Medium5	Divide and conquerRecursion+1	No attempts yet	2s	1024 MB	Judgeable
Permutation ProblemGiven n and k, find the k-th permutation of 1 to n in lexicographic order in which the numbers 1 and 2 are not adjacent.	Medium5	CombinatoricsBacktracking	No attempts yet	2s	1024 MB	Judgeable
LotteryCount the integers in the range [a..b] that are divisible by exactly k of the given n numbers.	Medium5	MathHash map+1	No attempts yet	1s	1024 MB	Judgeable
Figure SkatingPick each element score c_i in [b_i, a_i] so the total is m, minimizing the entry cost where 0 is free, one-digit scores cost x, and two-digit scores cost y.	Medium5	Dynamic programming	No attempts yet	2s	1024 MB	Judgeable
Enigmatic NumberSplit the decimal string N into the fewest pieces taken from a given set of up to 1000 numbers below 1000, using each number at most once.	Medium5	Dynamic programmingString+1	No attempts yet	2s	1024 MB	Judgeable
Sign Flip TableFind a sequence of row and column sign flips so every row and column sum of an integer table is non-negative, using at most 20000 moves.	Medium5	MatrixGreedy+1	No attempts yet	2s	1024 MB	Judgeable
TramsGiven a tree and m paths between pairs of vertices, count the edges that no path passes through.	Medium5	TreeDFS+1	No attempts yet	5s	1024 MB	Judgeable
IslandsGiven islands joined by bridges where each island has at most two, find the total shortest-path toll over all reachable ordered island pairs.	Medium5	GraphMath+1	No attempts yet	2s	1024 MB	Judgeable
Oil MiningFind an axis-parallel subrectangle of an n by m grid whose cell sum equals S, and print its upper-left and lower-right corners, or -1 if none exists.	Medium5	MatrixPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Role-Playing GamePick tasks whose prerequisites are all done, keep total time within m minutes, maximize total experience, and print one valid completion order.	Medium5	Dynamic programmingBit manipulation	No attempts yet	2s	1024 MB	Judgeable
How Many Stars Are in the Sky?Given N integer points and M axis-aligned rectangles, count the points inside or on the boundary of each rectangle.	Medium5	SortingPrefix sum+1	No attempts yet	4s	1024 MB	Judgeable
Tampered RecordsGiven n ranked pairs of solve counts where some values may be overwritten, find the fewest values to change so the list is sorted by afternoon, then morning, counts.	Medium5	Dynamic programmingBinary search	No attempts yet	8s	1024 MB	Judgeable
Bushil, the King of Short CodingDelete at most M of the N code lengths to maximize the sum of adjacent differences, which reduces to the last kept value minus the first.	Medium5	ArraySliding window	No attempts yet	1s	1024 MB	Judgeable
A Plus BGiven two sorted arrays A and B of length N, output the N smallest of all N^2 pairwise sums A[i] + B[j] in increasing order.	Medium5	HeapSorting	No attempts yet	1s	1024 MB	Judgeable
LazdynasGiven N nut coordinates, find the maximum number of nuts Squirrel Vytis can catch when the tree chooses the drop order.	Medium5	GreedyHash map+1	No attempts yet	1s	1024 MB	Judgeable
UntieGiven a circular string of R, P, and S, find the fewest characters to change so that no two neighboring characters are equal.	Medium5	Dynamic programmingString	No attempts yet	10s	1024 MB	Judgeable
Intruder OutsmartingEach wheel moves by plus or minus D on a cycle of N numbers. Find the fewest turns that make the wheel values a palindrome, or report that it is impossible.	Medium5	Number theoryMath+1	No attempts yet	5s	1024 MB	Judgeable
Railroad MaintenanceCount the train lines whose removal makes some pair of stations unreachable from each other, given the stations each line serves.	Medium5	GraphDFS	No attempts yet	40s	1024 MB	Judgeable
Game Sort: Part 1Given P strings, rearrange the letters inside each one so the resulting list is in non-decreasing lexicographic order, or report that it cannot be done.	Medium5	StringGreedy	No attempts yet	5s	1024 MB	Judgeable
TraitorGiven friendships and the traitor's number, find the size of the largest group after the traitor splits his group apart.	Medium5	GraphBFS+1	No attempts yet	1s	1024 MB	Judgeable
Doing Assignments EfficientlyPick a subset of assignments to do shortest-first, maximizing points (half for late work within 24 hours), then report the least total time that achieves that maximum.	Medium5	Dynamic programmingSorting	No attempts yet	1s	1024 MB	Judgeable
Two Pointers (easy version)Given city positions and the starts of Alice and Bob, find the minimum total distance so every city is visited by one of them.	Medium5	SortingTwo pointers+1	No attempts yet	1s	1024 MB	Judgeable
Love LetterGiven dragons with distinct ages and free friend links, find the minimum letter-passing time from dragon 1 to every dragon.	Medium5	Shortest pathGraph+1	No attempts yet	2.5s	1024 MB	Judgeable
FoldersFind the minimum number of cursor moves to open the target file when each folder list can be reversed once with a button above its first item.	Medium5	Dynamic programmingImplementation	No attempts yet	1s	1024 MB	Judgeable
Domino StonesSplit N domino stones into two boxes so no symbol repeats within a box, or report impossible; print the lexicographically smallest split.	Medium5	GraphBFS	No attempts yet	1.5s	1024 MB	Judgeable
Word GroupsGiven N words over R letters, find the fewest letters so that every word contains at least one of the chosen letters.	Medium5	Bit manipulationBrute force+1	No attempts yet	0.1s	1024 MB	Judgeable