Problems

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Total results29,466 problems

Bipartite Graph
Medium4
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Polynomial Remainders
Medium4
Math, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Parcel Routing
Medium4
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Permutation Order
Medium4
Math, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Painting Board Piece Sizes
Medium4
BFS, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sums of Powers of Three
Medium4
Math, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Shortest Path
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Problem Solving Order
Medium4
Topological sort, Heap+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Center of Symmetry
Medium4
Hash map, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Different Religions on Campus
Medium4
Union-find, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Search
Medium4
String matching, String
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
K-th Digit in a Concatenated Number String
Medium4
Math, Binary search+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Partial Sum
Medium4
Sliding window, Two pointers+1
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Candy
Medium4
Math, Array+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Card Magic
Medium4
Simulation, Queue+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Wormholes
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Stack Sequence
Medium4
Stack, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Jump
Medium4
Dynamic programming, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ripple Effect
Medium4
Union-find, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Snail Table
Medium4
Simulation, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Largest Square
Medium4
Dynamic programming, Matrix
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimum Cost Path
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Postfix Notation
Medium4
Stack, String
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Network Connection
Medium4
Minimum spanning tree, Union-find+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Tetrahedron Equivalence
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Digital Clock
Medium4
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
New Employees
Medium4
Sorting, Greedy
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Gift Exchange
Medium4
Dynamic programming, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Printing Types
Medium4
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Team Assignment
Medium4
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Exercise Route
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
192 MB
Judgeable
LCS of Three Strings
Medium4
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Box Nesting
Medium4
Dynamic programming, Binary search+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Diameter of a Tree
Medium4
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Quad Tree Compression
Medium4
Divide and conquer, Recursion+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Chemistry 101
Medium4
String, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Decode Count
Medium4
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum of Numbers 4
Medium4
Prefix sum, Hash map+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Remarkable Primes
Medium4
Backtracking, Math+1
No attempts yet
Time limit
2s
Memory limit
4 MB
Judgeable
Matchstick Grid
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Range Sum Query with Updates
Medium4
Segment tree, Array+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Exponential Operation
Medium4
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
8 MB
Judgeable
Minimum Time to Complete Tasks
Medium4
Dynamic programming, Topological sort+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Good Password
Medium4
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Infinite Binary Tree
Medium4
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Digital Clock
Medium4
Brute force, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Harmonic Average
Medium4
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Coins
Medium4
Greedy, Brute force+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Router Installation
Medium4
Binary search, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Circular Dance
Medium4
Math, Combinatorics
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Transaction Limit Checking
Medium4
Hash map, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tiling a 3-by-N Wall
Medium4
Dynamic programming, Combinatorics
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Post Office
Medium4
Sorting, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Ordered Array
Medium4
Matrix, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cipher Decryption
Medium4
String, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Writing Consecutive Numbers 3
Medium4
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cake Delivery
Medium4
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Robot Simulation
Medium4
Simulation, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cutting Land
Medium4
Geometry, Brute force+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Kimchi Delivery
Medium4
Greedy, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Barn Assignment
Medium4
Graph, Greedy
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Custom Table Sorter
Medium4
Sorting, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Collecting Jewels
Medium4
Prefix sum, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Board Jump
Medium4
DFS, Brute force+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sensors
Medium4
Sorting, Greedy
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maximum Independent Set in a Tree
Medium4
Dynamic programming, Tree+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
String Alignment Score
Medium4
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Proving Propositions
Medium4
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Choose Two Numbers With Minimum Difference
Medium4
Sorting, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Choosing Condos
Medium4
Sorting, Greedy
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Find the Binary Number
Medium4
Combinatorics, Binary search+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Student Lineup
Medium4
Topological sort, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Building a Tree
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Chemical Formula Mass
Medium4
Stack, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Symmetric Drawing
Medium4
Math, Hash map+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum of Numbers 7
Medium4
Segment tree, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Post Office
Medium4
Sorting, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Coin 1
Medium4
Dynamic programming
No attempts yet
Time limit
0.5s
Memory limit
4 MB
Judgeable
Large Integer Arithmetic
Medium4
Math, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Guitar Lesson
Medium4
Binary search, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Popping Balloons
Medium4
Simulation, Linked list+1
No attempts yet
Time limit
2s
Memory limit
4 MB
Judgeable
Semiconductor Design
Medium4
Dynamic programming, Binary search
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Minimum and Maximum
Medium4
Segment tree, Array
No attempts yet
Time limit
2s
Memory limit
192 MB
Judgeable
Maximum Distance
Medium4
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Keyword Matching
Medium4
Sorting, Hash map+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum of Distances
Medium4
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Three Numbers, Two Ms
Medium4
Sorting, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Large Number Calculation
Medium4
Math, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Word Grid
Medium4
Dynamic programming, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
File Similarity Checks
Medium4
Sorting, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Finding Silent Intervals
Medium4
Sliding window, Queue+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Smallest Unmeasurable Weight
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Password
Medium4
Bit manipulation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Two Liquids Closest to Zero
Medium4
Two pointers, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Safe Areas
Medium4
BFS, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Two Liquids
Medium4
Two pointers, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hamming Path
Medium4
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Color Wheel
Medium4
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Street Trees
Medium4
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shuffle Sequence
Medium4
Math, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Bipartite GraphFor several undirected graphs, determine whether each one can be 2-colored so that no edge joins two vertices of the same color.	Medium4	GraphBFS+1	No attempts yet	2s	256 MB	Judgeable
Polynomial RemaindersCompute the remainder polynomial when dividing a given polynomial by x^k + 1, using the fact that x^k ≡ -1.	Medium4	MathArray+1	No attempts yet	1s	128 MB	Judgeable
Parcel RoutingGiven a weighted graph, compute for every pair of hubs the next hub to visit on a shortest path using all-pairs shortest paths.	Medium4	Shortest pathGraph+2	No attempts yet	2s	128 MB	Judgeable
Permutation OrderGiven N, either compute the k-th lexicographic permutation of 1..N or find the rank of a given permutation, using factorial number system logic.	Medium4	MathCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Painting Board Piece SizesGiven a grid with wall segments blocking movement between adjacent cells, find the largest and smallest connected region sizes using BFS or DFS.	Medium4	BFSDFS+2	No attempts yet	2s	128 MB	Judgeable
Sums of Powers of ThreeGiven N, find the Nth smallest positive integer that is a sum of distinct powers of three, using a base-2 to base-3 digit mapping.	Medium4	MathBit manipulation+1	No attempts yet	2s	128 MB	Judgeable
Shortest PathCompute single source shortest paths from a given vertex in a directed weighted graph with up to 20,000 vertices and 300,000 edges, printing INF for unreachable vertices.	Medium4	Shortest pathGraph+1	No attempts yet	1s	256 MB	Judgeable
Problem Solving OrderGiven N tasks and M precedence constraints, output a topological order that always picks the smallest available problem number next.	Medium4	Topological sortHeap+1	No attempts yet	2s	128 MB	Judgeable
Center of SymmetryDecide whether a set of up to 10000 integer points has a center point such that every point's mirror image is also in the set.	Medium4	Hash mapGeometry+2	No attempts yet	1s	128 MB	Judgeable
Different Religions on CampusGiven pairs of students sharing a religion, compute the maximum number of distinct religions possible using union-find over multiple test cases.	Medium4	Union-findGraph	No attempts yet	1s	128 MB	Judgeable
String SearchImplement KMP string matching to count and list all 1-indexed starting positions where pattern P occurs in text T of length up to 1,000,000.	Medium4	String matchingString	No attempts yet	2s	256 MB	Judgeable
K-th Digit in a Concatenated Number StringGiven N and k, find the k-th digit in the concatenation of integers 1 through N, or -1 if the string is shorter than k.	Medium4	MathBinary search+1	No attempts yet	2s	64 MB	Judgeable
Partial SumFind the minimum length of a contiguous subarray whose sum is at least S, or 0 if none exists.	Medium4	Sliding windowTwo pointers+1	No attempts yet	0.5s	128 MB	Judgeable
CandyGiven the sums of adjacent candy counts for N students seated in an odd-sized circle, recover each student's exact candy count.	Medium4	MathArray+1	No attempts yet	2s	128 MB	Judgeable
Card MagicFind an initial card order so that repeatedly cycling and dealing cards produces the sequence 1 to N on the table.	Medium4	SimulationQueue+1	No attempts yet	2s	128 MB	Judgeable
WormholesGiven roads with positive weights and wormholes with negative weights, detect whether any negative cycle exists in the resulting directed graph using Bellman-Ford.	Medium4	Shortest pathGraph+1	No attempts yet	2s	128 MB	Judgeable
Stack SequenceDetermine if a target permutation of 1 to n can be produced by a stack pushing values in increasing order, and output the push/pop sequence if possible.	Medium4	StackSimulation+1	No attempts yet	2s	128 MB	Judgeable
JumpCount the number of paths from top-left to bottom-right of a grid where each cell's value fixes the exact jump distance right or down.	Medium4	Dynamic programmingMatrix	No attempts yet	1s	128 MB	Judgeable
Ripple EffectValidate a filled Ripple Effect puzzle grid by checking polyomino region digit ranges and minimum-distance spacing rules for repeated numbers in rows and columns.	Medium4	Union-findSimulation+1	No attempts yet	2s	128 MB	Judgeable
Snail TableFill an N x N grid with numbers 1 to N^2 spiraling outward from the center and report the row and column of a given target number.	Medium4	SimulationMatrix+1	No attempts yet	2s	128 MB	Judgeable
Largest SquareGiven a binary grid, find the area of the largest square consisting entirely of 1s using dynamic programming.	Medium4	Dynamic programmingMatrix	No attempts yet	1s	128 MB	Judgeable
Minimum Cost PathGiven a directed weighted graph of cities and bus routes, compute the minimum cost path from a start city to a destination city.	Medium4	Shortest pathGraph+1	No attempts yet	0.5s	128 MB	Judgeable
Postfix NotationConvert a fully parenthesized-or-not infix arithmetic expression with single-letter operands into its postfix notation.	Medium4	StackString	No attempts yet	2s	128 MB	Judgeable
Network ConnectionGiven N computers and M weighted possible connections, compute the minimum total cost of edges to connect all computers into one network (minimum spanning tree).	Medium4	Minimum spanning treeUnion-find+1	No attempts yet	2s	256 MB	Judgeable
Tetrahedron EquivalenceDecide whether two tetrahedra with colored faces are equal under 3D rotation, given each as a base face plus three side faces in clockwise order.	Medium4	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
Digital ClockGiven three start-end time ranges on a 24-hour clock that may wrap past midnight, count how many seconds have a clock integer (hhmmss with colons removed) divisible by 3.	Medium4	SimulationMath+1	No attempts yet	2s	128 MB	Judgeable
New EmployeesGiven N applicants ranked by two criteria, count applicants not dominated in both ranks by any other applicant (classic sort plus max-suffix pattern).	Medium4	SortingGreedy	No attempts yet	2s	256 MB	Judgeable
Gift ExchangeCompute the number of derangements of N items modulo 1,000,000,000.	Medium4	Dynamic programmingMath+1	No attempts yet	2s	128 MB	Judgeable
Printing TypesCount the total number of digits used to write all integers from 1 to N, given modulo 1,234,567.	Medium4	MathImplementation	No attempts yet	2s	128 MB	Judgeable
Team AssignmentSplit students into two groups using graph two-coloring so no pair who dislike each other lands on the same team, printing both groups.	Medium4	GraphBFS+1	No attempts yet	2s	128 MB	Judgeable
Exercise RouteFind the minimum weight cycle in a directed graph with up to 400 vertices, essentially detecting the shortest cycle via all-pairs shortest paths.	Medium4	Shortest pathGraph+1	No attempts yet	2s	192 MB	Judgeable
LCS of Three StringsCompute the length of the longest common subsequence shared by three given strings using dynamic programming.	Medium4	Dynamic programmingString	No attempts yet	2s	128 MB	Judgeable
Box NestingFind the length of the longest strictly increasing subsequence of box sizes given in order.	Medium4	Dynamic programmingBinary search+1	No attempts yet	2s	128 MB	Judgeable
Diameter of a TreeGiven a weighted tree of up to 10,000 nodes rooted at node 1, compute the maximum-length path between any two nodes.	Medium4	TreeDFS+1	No attempts yet	2s	128 MB	Judgeable
Quad Tree CompressionGiven an N x N binary grid, recursively quadrant-compress it into a string using uniform-region shortcuts and parenthesized quadrant order.	Medium4	Divide and conquerRecursion+1	No attempts yet	2s	128 MB	Judgeable
Chemistry 101Parse a chemical equation with molecule multipliers and element counts, then report which elements differ in count between reagents and products.	Medium4	StringHash map+1	No attempts yet	1s	128 MB	Judgeable
Decode CountCount the number of ways to decode a digit string into letters A-Z, modulo 1,000,000.	Medium4	Dynamic programmingString	No attempts yet	2s	128 MB	Judgeable
Sum of Numbers 4Count the number of contiguous subarray sums of an array that equal a given target K, using prefix sums and a hash map.	Medium4	Prefix sumHash map+1	No attempts yet	2s	128 MB	Judgeable
Remarkable PrimesGiven N, output all N-digit primes whose every left-hand prefix (1 to N digits) is also prime, in ascending order.	Medium4	BacktrackingMath+1	No attempts yet	2s	4 MB	Judgeable
Matchstick GridGiven an ASCII 3x3 matchstick grid, count how many matchsticks were removed and how many complete squares of any size remain.	Medium4	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
Range Sum Query with UpdatesSupport point updates and range-sum queries on an array of up to a million integers using a Fenwick tree or segment tree.	Medium4	Segment treeArray+1	No attempts yet	2s	256 MB	Judgeable
Exponential OperationPrint the exact decimal expansion of 1/2^N without trailing zeros, for N up to 250, using big-number arithmetic.	Medium4	MathImplementation+1	No attempts yet	2s	8 MB	Judgeable
Minimum Time to Complete TasksGiven tasks with durations and prerequisites forming a DAG (prerequisites always have smaller index), compute the minimum total time to finish all tasks using longest path via DP.	Medium4	Dynamic programmingTopological sort+1	No attempts yet	2s	256 MB	Judgeable
Good PasswordGiven a huge number K up to 10^100 and threshold L, find K's smallest prime factor and check whether it is at least L.	Medium4	Number theoryMath+1	No attempts yet	2s	128 MB	Judgeable
Infinite Binary TreeGiven target pair (A,B) reachable in an infinite binary tree defined by additive child rules, count the left and right moves needed via a Euclidean-like reverse process.	Medium4	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Digital ClockGiven a broken 5x3 segment display for four digits where lit cells are always correct but some are missing, find the earliest valid hh:mm time consistent with the pattern.	Medium4	Brute forceImplementation+1	No attempts yet	2s	128 MB	Judgeable
Harmonic AverageCompute the harmonic average of up to 9 natural numbers as a reduced fraction, printing the shortest, lexicographically smallest equivalent representation.	Medium4	MathImplementation	No attempts yet	2s	128 MB	Judgeable
CoinsGiven limited counts of coins worth 1, 5, 10, and 25 cents, find the combination summing to exactly X cents that uses the maximum total number of coins.	Medium4	GreedyBrute force+1	No attempts yet	2s	128 MB	Judgeable
Router InstallationGiven house coordinates, place C routers among them to maximize the minimum pairwise distance between chosen routers.	Medium4	Binary searchGreedy+1	No attempts yet	2s	128 MB	Judgeable
Circular DanceGiven N people in a circle, compute the minimum adjacent swaps needed to reverse their order up to rotation, which reduces to a closed-form floor formula.	Medium4	MathCombinatorics	No attempts yet	2s	128 MB	Judgeable
Transaction Limit CheckingParse bank customer, account, and transaction records to validate ownership and per-day, per-type transaction and exposure limits, printing a result per instruction.	Medium4	Hash mapSimulation+1	No attempts yet	1s	128 MB	Judgeable
Tiling a 3-by-N WallCount the number of ways to tile a 3-by-N wall using 2x1 dominoes, for N up to 30.	Medium4	Dynamic programmingCombinatorics	No attempts yet	2s	128 MB	Judgeable
Post OfficeGiven villages with positions and populations on a line, find the point minimizing total weighted distance, choosing the smallest position on ties.	Medium4	SortingPrefix sum+1	No attempts yet	2s	128 MB	Judgeable
Ordered ArrayCheck whether a given 2D array satisfies the Monge-like inequality A[i][j]+A[k][l] ≤ A[i][l]+A[k][j] for all row and column pairs, using adjacent checks only.	Medium4	MatrixImplementation+1	No attempts yet	2s	128 MB	Judgeable
Cipher DecryptionGiven a key and ciphertext produced by a columnar transposition cipher, reconstruct the original plaintext.	Medium4	StringSimulation+1	No attempts yet	2s	128 MB	Judgeable
Writing Consecutive Numbers 3Given N, find the earliest 1-based index where the digit-string of N occurs inside the concatenation of integers 1 through N.	Medium4	String matchingString+1	No attempts yet	2s	128 MB	Judgeable
Cake DeliveryCompute the minimum total grid-walk distance to visit N customers in fixed order, where reaching any of the 4 neighbors of a customer point counts as delivery.	Medium4	GreedyMath+1	No attempts yet	2s	128 MB	Judgeable
Robot SimulationSimulate robots moving on a grid according to turn and move commands and report the first wall or robot collision, or OK if none occurs.	Medium4	SimulationImplementation	No attempts yet	2s	128 MB	Judgeable
Cutting LandGiven a convex quadrilateral, find the cut between two vertices or side-midpoints that splits it into two polygons with the most balanced areas.	Medium4	GeometryBrute force+1	No attempts yet	2s	128 MB	Judgeable
Kimchi DeliveryGiven N cities on a line and a starting point, find the order of visiting all cities minimizing the sum of arrival times.	Medium4	GreedyDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Barn AssignmentGiven each cow's list of acceptable stalls, find the maximum number of cows that can be matched to distinct stalls using bipartite matching.	Medium4	GraphGreedy	No attempts yet	2s	128 MB	Judgeable
Custom Table SorterRead tables and per-line sort specifications, then output the table rows stably sorted by given field/direction keys for each specification, grouped and formatted with blank lines.	Medium4	SortingString+1	No attempts yet	1s	128 MB	Judgeable
Collecting JewelsGiven N values in a line, find the maximum sum of a single contiguous run of length at least M taken once.	Medium4	Prefix sumDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Number Board JumpCount the distinct length-6 digit strings obtainable by starting anywhere on a 5x5 digit board and making five moves to adjacent cells.	Medium4	DFSBrute force+1	No attempts yet	2s	128 MB	Judgeable
SensorsGiven N sensor coordinates and up to K interval-shaped concentrators, find the minimum total interval length needed to cover all sensors.	Medium4	SortingGreedy	No attempts yet	2s	128 MB	Judgeable
Maximum Independent Set in a TreeGiven a weighted tree, compute a maximum weight independent set using tree DP and output the chosen vertices.	Medium4	Dynamic programmingTree+1	No attempts yet	2s	128 MB	Judgeable
String Alignment ScoreCompute the maximum scoring alignment of two strings using gap and mismatch/match scoring, which is a classic sequence alignment (edit distance style) DP.	Medium4	Dynamic programmingString	No attempts yet	2s	128 MB	Judgeable
Proving PropositionsGiven directed edges between letters, compute the transitive closure and print all reachable pairs excluding self-loops, sorted by letter order.	Medium4	GraphDFS+1	No attempts yet	2s	128 MB	Judgeable
Choose Two Numbers With Minimum DifferenceGiven N integers and threshold M, find the minimum absolute difference between two elements that is still at least M.	Medium4	SortingTwo pointers+1	No attempts yet	2s	128 MB	Judgeable
Choosing CondosCount condos that are Pareto-optimal, having no other condo that is both closer to the beach and cheaper.	Medium4	SortingGreedy	No attempts yet	2s	128 MB	Judgeable
Find the Binary NumberGiven N, L, and I, output the I-th binary string of length N (with at most L ones) in increasing numeric order.	Medium4	CombinatoricsBinary search+1	No attempts yet	2s	128 MB	Judgeable
Student LineupGiven precedence constraints between N students, output any ordering consistent with all constraints, i.e. a topological sort.	Medium4	Topological sortGraph+1	No attempts yet	2s	128 MB	Judgeable
Building a TreeFind a spanning tree rooted at R that minimizes the sum of parent degrees over all non-root vertices, using a BFS-like greedy shortest path with degree as edge weight.	Medium4	Shortest pathGraph+1	No attempts yet	2s	128 MB	Judgeable
Chemical Formula MassParse a chemical formula with nested parentheses and digit multipliers to compute the total atomic mass using H=1, C=12, O=16.	Medium4	StackString+1	No attempts yet	2s	128 MB	Judgeable
Symmetric DrawingGiven N marked points, decide if there is a vertical line x=c so that folding the plane along it maps the point set onto itself, and output that x-coordinate or NO.	Medium4	MathHash map+1	No attempts yet	2s	128 MB	Judgeable
Sum of Numbers 7Support point updates and range sum queries on an array of up to 1,000,000 elements over up to 1,000,000 operations, requiring a Fenwick tree or segment tree.	Medium4	Segment treePrefix sum+1	No attempts yet	2s	256 MB	Judgeable
Post OfficeGiven village coordinates and resident counts, find the smallest position minimizing total weighted distance to all residents (weighted median).	Medium4	SortingPrefix sum+1	No attempts yet	2s	128 MB	Judgeable
Coin 1Given n coin denominations, count the number of combinations (order irrelevant, unlimited supply) that sum exactly to k.	Medium4	Dynamic programming	No attempts yet	0.5s	4 MB	Judgeable
Large Integer ArithmeticCompute the sum, difference, and product of two signed integers up to 1000 digits without built-in bignum support.	Medium4	MathString+1	No attempts yet	2s	128 MB	Judgeable
Guitar LessonSplit an ordered array into M contiguous groups so the maximum group sum is as small as possible, using binary search on the answer.	Medium4	Binary searchGreedy+1	No attempts yet	2s	128 MB	Judgeable
Popping BalloonsSimulate popping balloons arranged in a circle, moving left or right by the value on each popped balloon among remaining balloons.	Medium4	SimulationLinked list+1	No attempts yet	2s	4 MB	Judgeable
Semiconductor DesignGiven a permutation of port connections, find the longest increasing subsequence to avoid crossing lines.	Medium4	Dynamic programmingBinary search	No attempts yet	2s	128 MB	Judgeable
Minimum and MaximumGiven N numbers and M range queries, output the minimum and maximum value within each query's index range.	Medium4	Segment treeArray	No attempts yet	2s	192 MB	Judgeable
Maximum DistanceGiven up to 50,000 points, compute the maximum L1 (Manhattan) distance between any two of them.	Medium4	MathGreedy+1	No attempts yet	1s	128 MB	Judgeable
Keyword MatchingGiven weighted keyword lists for pages and queries, compute matching scores and output up to 5 top-scoring pages per query.	Medium4	SortingHash map+1	No attempts yet	2s	128 MB	Judgeable
Sum of DistancesGiven n points on a line, compute the sum of absolute distances over all ordered pairs efficiently using sorting and prefix sums.	Medium4	SortingPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Three Numbers, Two MsGiven n integers, pick three to maximize 3 times (median minus mean), which reduces to sorting and checking min/max extremes.	Medium4	SortingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Large Number CalculationParse and evaluate an arithmetic expression with big integers up to 10^100, respecting operator precedence and floor division for negatives.	Medium4	MathString+1	No attempts yet	2s	128 MB	Judgeable
Word GridCount the number of paths in an HxW grid moving to 8-directional neighbors (cells reusable) that spell out a given word of length L.	Medium4	Dynamic programmingMatrix+1	No attempts yet	1s	128 MB	Judgeable
File Similarity ChecksGiven N file sizes, count pairs where the smaller size is at least 0.9 times the larger size.	Medium4	SortingTwo pointers+1	No attempts yet	1s	128 MB	Judgeable
Finding Silent IntervalsFind every starting index of a length-m window in an array where the max minus min value is at most c, using a sliding window with monotonic deques.	Medium4	Sliding windowQueue+1	No attempts yet	1s	128 MB	Judgeable
Smallest Unmeasurable WeightGiven N integer weights usable only on one pan, find the smallest positive integer amount that cannot be formed as a subset sum.	Medium4	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
PasswordGiven integer A, find the nearest smaller and nearest larger integers with the same popcount as A, using bit manipulation, or print 0 if none exists.	Medium4	Bit manipulationMath+1	No attempts yet	1s	128 MB	Judgeable
Two Liquids Closest to ZeroGiven a sorted array, find two distinct numbers whose sum is closest to zero using a two-pointer sweep.	Medium4	Two pointersArray+1	No attempts yet	1s	128 MB	Judgeable
Safe AreasGiven an N x N height grid, find the rain level that maximizes the number of 4-connected regions of unsubmerged cells.	Medium4	BFSBrute force+1	No attempts yet	1s	128 MB	Judgeable
Two LiquidsGiven N distinct integers, sort them and use two pointers to find the pair whose sum is closest to zero.	Medium4	Two pointersSorting+1	No attempts yet	1s	128 MB	Judgeable
Hamming PathBuild a graph where binary codes connect if their Hamming distance is 1, then output a shortest path between two given codes via BFS.	Medium4	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Color WheelCount the ways to choose K non-adjacent colors from N colors arranged in a circle, modulo 1,000,000,003.	Medium4	CombinatoricsMath+1	No attempts yet	1s	128 MB	Judgeable
Street TreesGiven sorted tree positions, find the minimum number of trees to insert so all consecutive gaps equal the GCD of all gap sizes.	Medium4	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Shuffle SequenceGiven a permutation of size N, compute the least common multiple of its cycle lengths, which is the number of shuffles needed to restore the original order.	Medium4	MathArray+1	No attempts yet	1s	128 MB	Judgeable