Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,616 problems

Walk of Three
Medium5
Graph, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Wheel of Fortune
Medium5
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Text Formatting
Medium5
String, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Archery Championship
Medium5
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Diplomas
Medium5
Binary search, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dance School
Medium5
Prefix sum, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dodo's Math Game
Medium5
Sorting, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Histogram
Medium5
Implementation, Array+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Three Slices
Medium5
Binary search, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Typos
Medium5
Hash map, String
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Acowdemia I
Medium5
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Acowdemia II
Medium5
Graph, Topological sort
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Border Restrictions
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Bubbles
Medium5
Union-find, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Undergraduate Researcher Minsang
Medium5
BFS, Simulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
City Construction
Medium5
Minimum spanning tree, Union-find+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Secrets of Legendary Treasure
Medium5
Greedy, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Maximize the Expression
Medium5
Brute force, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Build It on a Foundation Stone
Medium5
Sliding window, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Automatic Sprayer
Medium5
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Coin Collection
Medium5
Dynamic programming, Simulation
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Slot Machines
Medium5
Greedy, Implementation
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Game
Medium5
Dynamic programming, Probability+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Problem Review
Medium5
Dynamic programming, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Changyoung and the Jump
Medium5
Two pointers, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alien Message
Medium5
Combinatorics, String+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Postal Shipment
Medium5
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Tea Break
Medium5
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
k-sorting
Medium5
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Mines - 9
Medium5
Greedy, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Competition
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Neighborhood Watch
Medium5
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cipher
Medium5
String, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
On-Call
Medium5
Simulation, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Airport Codes
Medium5
String, Hash map+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
JAG-channel
Medium5
Implementation, Tree+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Invest Master
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Final Defense Line
Medium5
Geometry, Implementation
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
ReverseSort
Medium5
BFS, Brute force+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Calender Colors
Medium5
Brute force, Combinatorics+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Brave Force Story
Medium5
BFS, Graph+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Inviting Friends
Medium5
Intervals, Sorting+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Kaeru Jump
Medium5
Backtracking, DFS+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Ropeway
Medium5
Greedy, Math+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
CatChecker
Medium5
String, Dynamic programming+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Cache Control
Medium5
Hash map, Linked list+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Bitwise Kingdom
Medium5
Combinatorics, Binary search+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Building a Space Station
Medium5
Minimum spanning tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Get a Rectangular Field
Medium5
Brute force, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Certified Easy Game
Medium5
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Longest Even Contiguous Subsequence (small)
Medium5
Sliding window, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Restore the Original (small)
Medium5
Array, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Folder Cleanup (small)
Medium5
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Longest Even Contiguous Subsequence (Large)
Medium5
Sliding window, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Crossing the Stepping Stones (small)
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Binary Search Game
Medium5
Game theory, Dynamic programming+1
No attempts yet
Time limit
30s
Memory limit
1024 MB
Judgeable
Cookie Crew
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rotating maze zone search
Medium5
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Number of Increasing Subsequences
Medium5
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Image Shrinking
Medium5
Implementation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Smaller Strings
Medium5
Math, String+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Shuffled Anagrams
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
The Tasting Corner Is Mine
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Nutella Tree (Easy)
Medium5
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Challenge Number King
Medium5
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Flip Game
Medium5
Brute force, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Coloring Natural Numbers 2
Medium5
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bee Seungyeon
Medium5
Dynamic programming, Matrix+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Polish Notation
Medium5
Stack, Recursion+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Genetic Search
Medium5
String, Hash map+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fikapaus
Medium5
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Data Structures Are Really the Best
Medium5
Stack, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cloud Bridge 2
Medium5
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Banana Bunches
Medium5
Sliding window, Prefix sum+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Grazed Grains
Medium5
Geometry, Probability+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Joint Jog Jam
Medium5
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Entopia's Memory Boost
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Terminal Sequence
Medium5
Tree, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Choosing Study Time 2
Medium5
Prefix sum, Intervals+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rolling a Marble
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Graduation Photo
Medium5
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
K Logistics Warehouse
Medium5
Simulation, Stack+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Match Fixing
Medium5
Array, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fair Play
Medium5
Hash map, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Handling the Blocks
Medium5
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Multiplication and Division by 2
Medium5
Bit manipulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Removing Pairs
Medium5
String, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cubic polynomials
Medium5
Number theory, Hash map+1
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Wise man
Medium5
Simulation, Hash map+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Meal
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Wall Climbing
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Product
Medium5
Math, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Array
Medium5
Math, Greedy
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Subnumber Sum
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Shell Game
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Frog
Medium5
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Matchsticks
Medium5
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Power Outlets
Medium5
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Trimming the Tree
Medium5
Greedy, Tree+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Battle of Giants
Medium5
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Walk of ThreeCount walks of exactly three edges that start at vertex 1 and end at a neighbor of vertex 1 in a simple undirected graph.	Medium5	GraphCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Wheel of FortuneGiven n sector values on a circular wheel, a slowdown k per boundary crossing, and an initial velocity in [a, b], find the largest sector value the arrow can stop on when spinning either direction.	Medium5	MathImplementation+2	No attempts yet	2s	512 MB	Judgeable
Text FormattingReformat a text into paragraphs, each indented by b spaces and wrapped greedily at width w, with punctuation glued to the preceding word.	Medium5	StringSimulation+2	No attempts yet	2s	512 MB	Judgeable
Archery ChampionshipGiven a sequence of scores, find the best possible place of a participant whose score ends in 5, has a champion before him, and is followed immediately by a lower score.	Medium5	ArrayImplementation+2	No attempts yet	2s	512 MB	Judgeable
DiplomasGiven n identical w by h rectangles, find the smallest square side length that can contain all of them without overlaps.	Medium5	Binary searchMath+2	No attempts yet	2s	512 MB	Judgeable
Dance SchoolGiven a string of 'a' and 'b' of length up to 10^6, count the substrings in which the number of a's equals the number of b's.	Medium5	Prefix sumHash map+2	No attempts yet	2s	512 MB	Judgeable
Dodo's Math GameGiven N numbers, order and concatenate them so that the 180-degree rotated result is as large as possible, then print that value.	Medium5	SortingString+1	No attempts yet	2s	1024 MB	Judgeable
HistogramCount occurrences of each non-whitespace character in a text and print a vertical histogram of # bars sorted by character code.	Medium5	ImplementationArray+2	No attempts yet	2s	1024 MB	Judgeable
Three SlicesFind the largest M such that the array contains three consecutive blocks of length M, each with sum at most K.	Medium5	Binary searchPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
TyposFor each checked word, count the dictionary words that become identical to it after removing at most one letter from each word.	Medium5	Hash mapString	No attempts yet	2s	64 MB	Judgeable
Acowdemia IGiven N papers with citation counts and a budget of L extra citations (each paper cited at most once), find the maximum achievable h-index.	Medium5	SortingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Acowdemia IIGiven K author lists ordered by effort, determine for each pair of N lab members whether one is definitely more senior, using alphabetical tie-breaks.	Medium5	GraphTopological sort	No attempts yet	1s	512 MB	Judgeable
Border RestrictionsGiven N countries and which origins each country admits travellers from, find the week the virus reaches every country starting from the first listed, or 0 if it never arrives.	Medium5	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
BubblesEach person sits in one of P personal bubbles and one of W work bubbles, every personal bubble meets every work bubble in exactly one person; given infected bubbles, count infected people.	Medium5	Union-findGraph+2	No attempts yet	1s	256 MB	Judgeable
Undergraduate Researcher MinsangCount the cells reached by wind from all air conditioners on a grid where four object types redirect the wind.	Medium5	BFSSimulation+1	No attempts yet	1s	512 MB	Judgeable
City ConstructionGiven a connected weighted undirected graph, compute the total edge cost minus the cost of a minimum spanning tree, or -1 if the graph is disconnected.	Medium5	Minimum spanning treeUnion-find+2	No attempts yet	1s	512 MB	Judgeable
Secrets of Legendary TreasureTwo ascending sequences of distinct numbers from 1 to n+m are given with some entries erased to 0; restore any valid pair.	Medium5	GreedyArray+2	No attempts yet	1s	512 MB	Judgeable
Maximize the ExpressionArrange N given positive integers with P addition and Q multiplication operators, in any order and with any parentheses, to maximize the result.	Medium5	Brute forceBacktracking+2	No attempts yet	1s	512 MB	Judgeable
Build It on a Foundation StoneFind the longest contiguous subarray whose maximum minus minimum is at most 2, given values from 1 to 10.	Medium5	Sliding windowTwo pointers+2	No attempts yet	1s	512 MB	Judgeable
Automatic SprayerGiven the 8x8 yields after sprayers were placed, recover which plots hold a fertilizer sprayer, a herbicide sprayer, or nothing.	Medium5	Brute forceImplementation+2	No attempts yet	1s	512 MB	Judgeable
Coin CollectionGiven n cells that each gain a_i coins per second, find the most coins a character can collect in t seconds by staying or moving to an adjacent cell.	Medium5	Dynamic programmingSimulation	No attempts yet	3s	256 MB	Judgeable
Slot MachinesDecide whether some sequence of lamp on and off buttons turns all lamps from off into the target pattern, and print one such sequence if it exists.	Medium5	GreedyImplementation	No attempts yet	2s	256 MB	Judgeable
GameEach room has two corridors to the next level; a player always takes the shorter one and picks randomly on ties. Compute the expected total path length from the first level to the last.	Medium5	Dynamic programmingProbability+2	No attempts yet	2s	256 MB	Judgeable
Problem ReviewEach of m problems must be reviewed in order by a jury member willing to review it; switching reviewers costs c seconds, so find the minimum total time.	Medium5	Dynamic programmingImplementation+2	No attempts yet	2s	256 MB	Judgeable
Changyoung and the JumpGiven gaps between N red blocks and a stride K, find the longest run of blocks he can step through using at most one jump over a too-large gap.	Medium5	Two pointersSliding window+2	No attempts yet	2s	512 MB	Judgeable
Alien MessageGiven a string of a, b, and ?, count how many ways to replace ? yield a string that is not two identical halves, modulo 1e9+7.	Medium5	CombinatoricsString+2	No attempts yet	2s	256 MB	Judgeable
Postal ShipmentSplit up to 14 items into parcels so that each parcel costs its total weight in rubles, except parcels of exactly 1000 grams which cost P, and minimize the total.	Medium5	Dynamic programmingBit manipulation+2	No attempts yet	2s	256 MB	Judgeable
Tea BreakEach of n employees has a set of favorite tea kinds, and given a_i bags of each kind, find how many days everyone can drink a favorite tea.	Medium5	Binary searchGreedy+2	No attempts yet	2s	256 MB	Judgeable
k-sortingGiven an array and a fixed step k, find the minimum number of swaps of elements exactly k positions apart needed to sort the array in nondecreasing order, or -1 if impossible.	Medium5	SortingGreedy+2	No attempts yet	2s	256 MB	Judgeable
Mines - 9Given the 3x3 neighborhood mine counts for each cell of an H by W grid, restore which cells contain mines.	Medium5	GreedyImplementation+1	No attempts yet	1s	512 MB	Judgeable
CompetitionAssign every student to either a Physics team of size a or a Biology team of size b to maximize the total score.	Medium5	GreedySorting+1	No attempts yet	1s	512 MB	Judgeable
Neighborhood WatchGiven which houses on a line are watch houses, count the unordered pairs of houses whose connecting walk passes through at least one watch house.	Medium5	MathCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
CipherFor each Caesar-cipher message, try all 26 shifts, pick the one matching the most known threat and non-threat words, then print the plaintext and match percentages.	Medium5	StringBrute force+2	No attempts yet	1s	512 MB	Judgeable
On-CallCount how many times an alert turns on given a stream of per-minute error counts, a high threshold U, a low threshold L, and a window length D.	Medium5	SimulationSliding window+2	No attempts yet	2s	512 MB	Judgeable
Airport CodesFor each set of airport names, find the smallest k so that the derived codes (first letter plus letters after vowels, truncated to k) are all distinct, or report -1.	Medium5	StringHash map+2	No attempts yet	8s	512 MB	Judgeable
JAG-channelEach line is a post indented by dots; redraw the dots as spaces, mark each post's own dot with '+', and draw '\|' between a parent and its descendants.	Medium5	ImplementationTree+2	No attempts yet	8s	512 MB	Judgeable
Invest MasterGiven predicted prices for n stocks over d days, buy and sell units to maximize cash on the last day, with no fees and no intraday price change.	Medium5	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Final Defense LineGiven up to 5 polygons with gas concentrations and spawn and facility point pairs, find the minimum total damage a creature takes on its route.	Medium5	GeometryImplementation	No attempts yet	3s	512 MB	Judgeable
ReverseSortGiven a permutation of 1 to N, find the minimum number of subarray reversals needed to sort it into ascending order.	Medium5	BFSBrute force+2	No attempts yet	5s	512 MB	Judgeable
Calender ColorsChoose M of N Lab colors maximizing the sum of squared Euclidean distances over all pairs in the chosen subset.	Medium5	Brute forceCombinatorics+2	No attempts yet	5s	512 MB	Judgeable
Brave Force StoryCount how many hexagonal cells a piece can reach in at most t turns on a grid with obstacles, given axial coordinates and a starting cell.	Medium5	BFSGraph+2	No attempts yet	8s	512 MB	Judgeable
Inviting FriendsEach friend accepts a group size in [ai, bi]; the group includes me, so find the size s maximizing how many intervals contain s, then subtract one.	Medium5	IntervalsSorting+2	No attempts yet	8s	512 MB	Judgeable
Kaeru JumpFind a sequence of jumps for a frog on a grid of lily pads, where each departed leaf sinks, until only one leaf remains.	Medium5	BacktrackingDFS+1	No attempts yet	8s	512 MB	Judgeable
RopewayGiven packages in order, decide whether each one can be placed on a car of length L at distance at least R from the center without the moment sum exceeding M.	Medium5	GreedyMath+1	No attempts yet	8s	512 MB	Judgeable
CatCheckerDecide whether a string of m, e, w matches the grammar CAT := "" \| 'm' CAT 'e' CAT 'w'.	Medium5	StringDynamic programming+2	No attempts yet	8s	512 MB	Judgeable
Cache ControlSimulate an LRU cache of size M over N key accesses, then print the keys still cached from most to least recently used.	Medium5	Hash mapLinked list+2	No attempts yet	8s	512 MB	Judgeable
Bitwise KingdomGiven N and M, find the binary string of length N whose M-th lowest class ranking orders by popcount first, then lexicographic order.	Medium5	CombinatoricsBinary search+2	No attempts yet	8s	512 MB	Judgeable
Building a Space StationGiven n spheres in 3D, connect them all with minimum total corridor length, where two spheres are already linked if they touch or overlap.	Medium5	Minimum spanning treeGraph+2	No attempts yet	2s	512 MB	Judgeable
Get a Rectangular FieldFor each 5x5 grid of 0s and 1s, report the largest number of 1s contained in an all-ones axis-aligned rectangle.	Medium5	Brute forceArray+2	No attempts yet	2s	512 MB	Judgeable
Certified Easy GameStarting from 1, two players alternate adding a divisor of the current number to it; whoever pushes the value past K loses. Determine the winner under optimal play.	Medium5	Game theoryDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Longest Even Contiguous Subsequence (small)Delete at most K elements from a sequence, then report the longest contiguous run of even numbers possible.	Medium5	Sliding windowTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
Restore the Original (small)Given the deck after K shuffles and the shuffle order D, recover the original arrangement by applying the inverse shuffle K times.	Medium5	ArraySimulation+2	No attempts yet	1s	1024 MB	Judgeable
Folder Cleanup (small)Given a folder tree with files, answer queries that ask, for each folder, how many distinct file names and how many total files sit under it.	Medium5	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
Longest Even Contiguous Subsequence (Large)Given a sequence, delete at most K elements so that some remaining contiguous run consists only of even numbers, and report the longest such run.	Medium5	Sliding windowTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
Crossing the Stepping Stones (small)Given stones with values A_i, decide if you can reach the last stone when each jump i to j costs (j-i)*(1+\|A_i-A_j\|) and no jump may exceed K.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	1024 MB	Judgeable
Binary Search GameAlice and Bob alternately delete the left or right half of a 2L-cell board, and the task sums the final card score over all M^N card assignments.	Medium5	Game theoryDynamic programming+1	No attempts yet	30s	1024 MB	Judgeable
Cookie CrewOn an N x N grid with three of each topping type, find which topping type gives the shortest path from the house to the goal, visiting all three cells of that type.	Medium5	BFSGraph+2	No attempts yet	1s	512 MB	Judgeable
Rotating maze zone searchFind the fewest hours to reach the exit in a 4k by 4k maze where each hour you move or stay, then the 4x4 zone you stand in rotates 90 degrees clockwise.	Medium5	BFSGraph+1	No attempts yet	1s	1024 MB	Judgeable
Number of Increasing SubsequencesFor each position i, count the increasing subsequences that end at A_i, modulo 998244353, where values range up to 5000.	Medium5	Dynamic programmingPrefix sum+2	No attempts yet	2s	1024 MB	Judgeable
Image ShrinkingGiven an enlarged image formed by scaling each axis by an integer factor, recover an original image of smallest area.	Medium5	ImplementationBrute force+2	No attempts yet	2s	1024 MB	Judgeable
Smaller StringsCount length-N palindromes over the first K letters that are lexicographically smaller than S, modulo 1e9+7.	Medium5	MathString+2	No attempts yet	Not set	1024 MB	Judgeable
Shuffled AnagramsGiven a string, output a permutation of its letters with no letter in its original position, or report that none exists.	Medium5	GreedySorting+2	No attempts yet	Not set	1024 MB	Judgeable
The Tasting Corner Is MineGiven the food counts at N stalls, pick a subset with no three consecutive picks (at most two in a row) that maximizes total food, where the second stall of any two consecutive picks contributes only half its food rounded down.	Medium5	Dynamic programmingArray+1	No attempts yet	2s	512 MB	Judgeable
Nutella Tree (Easy)Count paths in a red/black tree that start at a black vertex and continue through only red vertices, with at least two vertices.	Medium5	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
Challenge Number KingGiven up to 20 card values, count how many integers from 1 to their total sum cannot be formed as a subset sum.	Medium5	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Flip GameGiven an N x N grid of 0/1 cells, find the fewest operations (flip a whole row or column, or one cell) to make all cells equal.	Medium5	Brute forceBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Coloring Natural Numbers 2Color the natural numbers 1 to N so that any two non-coprime numbers get different colors, using the fewest colors possible.	Medium5	Number theoryMath	No attempts yet	1s	1024 MB	Judgeable
Bee SeungyeonCount paths on an N by M hexagonal grid from cell (1,1) to (N,M), moving only down, up-right, or down-right, while avoiding K hole cells, modulo 1e9+7.	Medium5	Dynamic programmingMatrix+1	No attempts yet	1s	1024 MB	Judgeable
Polish NotationParse a prefix expression with +, -, * over integers and one-letter variables, then replace every variable-free subexpression with its computed value and print the result in prefix notation.	Medium5	StackRecursion+2	No attempts yet	2s	1024 MB	Judgeable
Genetic SearchFor each pair of DNA strings S and L, count exact occurrences in L of S, of every distinct one-deletion variant of S, and of every distinct one-insertion variant of S.	Medium5	StringHash map+2	No attempts yet	2s	1024 MB	Judgeable
FikapausBoth people move at constant speed between consecutive destinations; find the time when the distance between them is smallest.	Medium5	GeometryMath+2	No attempts yet	2s	1024 MB	Judgeable
Data Structures Are Really the BestGiven M stacks of distinct books numbered 1 to N, decide whether repeatedly taking only top books can yield the order 1, 2, ..., N.	Medium5	StackSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Cloud Bridge 2Color each building so adjacent buildings differ, and among all valid colorings output the one whose color sequence is lexicographically smallest.	Medium5	GraphGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Banana BunchesGiven tree bunch counts, find the fewest trees to buy so the chosen trees form at most two contiguous blocks summing to exactly K, or -1 if impossible.	Medium5	Sliding windowPrefix sum+1	No attempts yet	20s	1024 MB	Judgeable
Grazed GrainsGiven up to 10 circles, output the area of their union within 10% relative error, which Monte Carlo sampling can approximate.	Medium5	GeometryProbability+2	No attempts yet	3s	1024 MB	Judgeable
Joint Jog JamBoth runners move at constant speed along straight lines from their start points to their end points; find the maximum distance between them over the run.	Medium5	GeometryMath+2	No attempts yet	1s	1024 MB	Judgeable
Entopia's Memory BoostOn a fixed 3x4 board with two thumbs that move one at a time, press a given sequence of cells minimizing movement plus press costs A and B.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	1024 MB	Judgeable
Terminal SequenceGiven the Prufer-style removal sequence of a labeled tree, reconstruct all N-1 edges and print them in sorted order.	Medium5	TreeImplementation+2	No attempts yet	2s	1024 MB	Judgeable
Choosing Study Time 2Given each participant's available time intervals and a fixed study duration T, choose the start time that maximizes the total overlapping attendance time.	Medium5	Prefix sumIntervals+2	No attempts yet	1s	512 MB	Judgeable
Rolling a MarbleA marble starts at gap (0,0) and rolls down n rows, moving left or right at each row; count paths that pass through all m required gaps.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	0.5s	1024 MB	Judgeable
Graduation PhotoDeduplicate submissions by name, then find the (place, time) pair with the most people, breaking ties by lexicographically smallest place and earliest time.	Medium5	Hash mapSorting+2	No attempts yet	1s	512 MB	Judgeable
K Logistics WarehouseSimulate a rail of containers processed by priority, rearranging equal-priority stacks by weight and summing every weight lifted.	Medium5	SimulationStack+2	No attempts yet	1s	512 MB	Judgeable
Match FixingOn an N x N gomoku board, flip exactly one white stone to black so the longest run of black stones in a row, column, or diagonal is as long as possible.	Medium5	ArrayBrute force+2	No attempts yet	1s	512 MB	Judgeable
Fair PlayGiven n people each with billiards and pool skill values, decide whether they can be split into pairs so every pair has identical total skill in both categories.	Medium5	Hash mapSorting+2	No attempts yet	2s	1024 MB	Judgeable
Handling the BlocksGiven N blocks with distinct numbers and a color each, you may swap any two blocks of the same color; decide if the blocks can be sorted by number.	Medium5	GraphUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Multiplication and Division by 2Given two uint32 values x and y, decide whether repeated multiplication by 2 mod 2^32 and floor division by 2 can turn x into y.	Medium5	Bit manipulationMath+2	No attempts yet	2s	512 MB	Judgeable
Removing PairsDecide whether string s can be obtained from string t by repeatedly deleting two adjacent characters, where each deletion removes any neighboring pair.	Medium5	StringDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Cubic polynomialsGiven n cubic polynomials with integer coefficients, find the integer that is a root of their product with the largest multiplicity, and report that multiplicity.	Medium5	Number theoryHash map+1	No attempts yet	1.5s	256 MB	Judgeable
Wise manGiven A, M, and N, each day replace A with (A + the largest digit of A) mod M, and print A on day N.	Medium5	SimulationHash map+1	No attempts yet	1s	64 MB	Judgeable
MealPick one of two daily menu items for N days, staying within a total budget X, to maximize the sum of tastiness ratings.	Medium5	GreedySorting+2	No attempts yet	1s	256 MB	Judgeable
Wall ClimbingOn a grid with walls, each step costs 1 second but moving between two cells that both touch a wall is free; find the minimum time from S to E.	Medium5	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
ProductGiven up to 100,000 integers, decide whether one element equals the product of all the others and print such an element if it exists.	Medium5	MathArray+2	No attempts yet	1s	256 MB	Judgeable
ArrayRearrange the array so that taking the running value mod each later element leaves the largest possible final value.	Medium5	MathGreedy	No attempts yet	3s	256 MB	Judgeable
Subnumber SumSplit the digits of an N-digit number (N up to 18) into a K-digit subnumber and an (N-K)-digit subnumber, both keeping digit order, and maximize their sum.	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Shell GameGiven a start vertex and an exact number of moves Y, find every vertex reachable by a walk of length exactly Y in an undirected graph.	Medium5	GraphBFS+2	No attempts yet	1s	1024 MB	Judgeable
FrogGiven a string of K and P, split it into the fewest subsequences, each alternating between K and P, and output that count.	Medium5	GreedyString+2	No attempts yet	1s	512 MB	Judgeable
MatchsticksGiven N matchsticks, find any two-digit equation AB+CD=EF that uses exactly N sticks, counting two each for the plus and equals signs.	Medium5	Brute forceImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Power OutletsAssign N devices with power-of-two charge times to M identical outlets to finish all charging as early as possible.	Medium5	GreedyHeap+2	No attempts yet	1s	1024 MB	Judgeable
Trimming the TreeGiven a tree rooted at node 1 and a limit K per level, remove subtrees so that each level keeps at most K nodes, and find the maximum number of nodes kept.	Medium5	GreedyTree+2	No attempts yet	1s	1024 MB	Judgeable
The Battle of GiantsGiven a final score a:b, decide whether it can result from matches worth 3 points for a win and 1 for a draw, and if so print win, draw, win counts using the fewest matches.	Medium5	MathGreedy+1	No attempts yet	1s	512 MB	Judgeable