Problems

Pick a problem and write your solution in the built-in editor. The judge runs it against real test cases while you watch, and the wider archive is open to read whenever you like.

This page is still under construction.

Parts of this page are still being built. What you see may change.

Total results21,553 problems

Is the APC sorted from easy to hard?Easy2
Array, ImplementationNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Mission DonationEasy2
Implementation, MathNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Fastest FunctionEasy2
Math, ImplementationNo attempts yetTime limit1sMemory limit2048 MB
Judgeable
HI-ARCEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Similar Phone NumbersEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Big YieldEasy2
Math, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Chicken Dance Gomgomi Ims 2Easy2
Implementation, StringNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Redistributing the Setting FeesEasy2
Array, ImplementationNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Identify, Sort, Index, SolveEasy2
Sorting, Implementation +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
HCPC 2022 Problem SettingEasy2
Brute force, ImplementationNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Finding Maximal Non-Trivial MonotonesEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Mentors and MenteesEasy2
Sorting, StringNo attempts yetTime limit2sMemory limit256 MB
Judgeable
Vowel CountEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Soccer StandingsEasy2
Brute force, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Buying in BulkEasy2
Implementation, MathNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Are We Stopping Again?Easy2
Math, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Fold the Paper NicelyEasy2
Simulation, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Good Coin DenominationEasy2
Array, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
XOEasy2
Implementation, SimulationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
WalktoberEasy2
Array, ImplementationNo attempts yetTime limitNot setMemory limit1024 MB
Judgeable
CurlingEasy2
Implementation, MathNo attempts yetTime limit20sMemory limit1024 MB
Judgeable
Big NumberEasy2
Implementation, StringNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
SnowflakesEasy2
Implementation, ArrayNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
V for VendettaEasy2
Implementation, SimulationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Continuous?Easy2
Math, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Limit of a Sequence RatioEasy2
MathNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
ReverseEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
SquareEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
QuadraticsEasy2
Math, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
OrnamentsEasy2
Math, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
ZeroEasy2
Implementation, MathNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
DrawEasy2
ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
FriendsEasy2
Sorting, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
PresidentsEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Time LimitsEasy2
Implementation, MathNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
DateEasy2
Implementation, StringNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
BombEasy2
Matrix, SimulationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
ScaleEasy2
Array, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
PlaytimeEasy2
Implementation, MathNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Floor CleanerEasy2
Implementation, SortingNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
PalindromeEasy2
Two pointers, StringNo attempts yetTime limit5sMemory limit4 MB
Judgeable
Growth Potion Selection TicketEasy2
Implementation, Brute forceNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Choosing ProblemsEasy2
Hash map, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
A+BEasy2
String, ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
FarmEasy2
Math, ImplementationNo attempts yetTime limit0.15sMemory limit1024 MB
Judgeable
OczkoEasy2
Implementation, StringNo attempts yetTime limit2sMemory limit1024 MB
Judgeable
Horizontal HeartsEasy2
Implementation, StringNo attempts yetTime limit5sMemory limit1024 MB
Judgeable
Alternating wordEasy2
String, GreedyNo attempts yetTime limit4sMemory limit1024 MB
Judgeable
Non Classical ProblemEasy2
Implementation, MathNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
New TimeEasy2
Brute force, Math +1No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Kent-buggenEasy2
Hash map, StringNo attempts yetTime limit6sMemory limit1024 MB
Judgeable
Sum of a SequenceEasy3
Math, Brute force +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
TreasureEasy3
Greedy, Sorting +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
DivisorsEasy3
Math, Number theory +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
LiesEasy3
Union-find, Graph +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Guitar StringsEasy3
Brute force, Greedy +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Number SquareEasy3
Brute force, Matrix +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Tournament Meeting RoundEasy3
Simulation, Math +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
FriendsEasy3
Graph, Matrix +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
KingEasy3
Simulation, ImplementationNo attempts yetTime limit2sMemory limit128 MB
Judgeable
Leaf Nodes in a TreeEasy3
Tree, DFS +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
ZEasy3
Divide and conquer, Recursion +1No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Addition CycleEasy3
Simulation, MathNo attempts yetTime limit2sMemory limit128 MB
Judgeable
Minimum String DifferenceEasy3
String, Sliding window +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
UnderprimeEasy3
Number theory, Math +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Least Common Multiple of at Least Three NumbersEasy3
Math, Brute force +2No attempts yetTime limit2sMemory limit128 MB
Judgeable
RGB StreetEasy3
Dynamic programming, ArrayNo attempts yetTime limit0.5sMemory limit128 MB
Judgeable
Josephus PermutationEasy3
Queue, Simulation +1No attempts yetTime limit2sMemory limit256 MB
Judgeable
Come Back HomeEasy3
Backtracking, DFS +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Finding the RankEasy3
Array, Implementation +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Strange MultiplicationEasy3
Math, String +1No attempts yetTime limit2sMemory limit256 MB
Judgeable
Dice SumEasy3
Brute force, Math +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Student NumbersEasy3
String, Brute force +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Castle GuardsEasy3
Array, Greedy +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Switches On and OffEasy3
Simulation, Array +2No attempts yetTime limit2sMemory limit128 MB
Judgeable
Binary AdditionEasy3
String, Math +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Make a PalindromeEasy3
String, Brute force +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
DFS and BFSEasy3
DFS, BFS +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Alphabet DiamondEasy3
Simulation, Math +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Symmetric DifferenceEasy3
Hash map, Array +1No attempts yetTime limit2sMemory limit256 MB
Judgeable
War - Land GrabEasy3
Array, Hash mapNo attempts yetTime limit10sMemory limit512 MB
Judgeable
Shortcut Key AssignmentEasy3
Simulation, String +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Lee-myeon and Im-hyeonEasy3
Number theory, Implementation +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
BestsellerEasy3
Hash map, Sorting +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
D-DayEasy3
Math, ImplementationNo attempts yetTime limit2sMemory limit128 MB
Judgeable
Decimal DigitEasy3
Simulation, Math +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Knight TourEasy3
Simulation, Array +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Missed CallEasy3
Simulation, Implementation +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Arithmetic ProgressionEasy3
Math, ImplementationNo attempts yetTime limit2sMemory limit128 MB
Judgeable
Maze ConstructionEasy3
Simulation, Implementation +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
HockeyEasy3
Geometry, ImplementationNo attempts yetTime limit2sMemory limit128 MB
Judgeable
LotteryEasy3
Combinatorics, Math +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Binary to Octal ConversionEasy3
Bit manipulation, Math +2No attempts yetTime limit1sMemory limit128 MB
Judgeable
MessagesEasy3
Simulation, Array +2No attempts yetTime limit1sMemory limit128 MB
Judgeable
Six Degrees of Kevin BaconEasy3
BFS, Graph +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Eumha Railway 998Easy3
Geometry, MathNo attempts yetTime limit2sMemory limit128 MB
Judgeable
K-Sejun NumbersEasy3
Math, Number theory +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Serial NumbersEasy3
Sorting, String +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
Repairing Pipe LeaksEasy3
Greedy, Sorting +1No attempts yetTime limit2sMemory limit128 MB
Judgeable
WalkingEasy3
Math, GreedyNo attempts yetTime limit2sMemory limit128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Is the APC sorted from easy to hard?Given N distinct difficulty labels, check whether two problems were swapped, then print OK or KO with the two swapped difficulties in easy-to-hard order.	Easy2	ArrayImplementation	No attempts yet	1s	512 MB	Judgeable
Mission DonationFor each game, add up each mission's payout (K per kill, minus D per death, plus A per assist), skipping negative missions, and print the total.	Easy2	ImplementationMath	No attempts yet	1s	512 MB	Judgeable
Fastest FunctionGiven foo's percentage of total running time before and after an optimisation, output the factor by which foo itself got faster.	Easy2	MathImplementation	No attempts yet	1s	2048 MB	Judgeable
HI-ARCGiven a string of uppercase letters, find how many complete sets of H, I, A, R, and C can be taken to make HI-ARC emojis.	Easy2	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
Similar Phone NumbersCount the space-separated phone numbers in A that start with B and are not equal to B.	Easy2	StringImplementation	No attempts yet	1s	512 MB	Judgeable
Big YieldGiven the total milk L and the pouring time T, find the difference between the two buckets' amounts, where the longer pour equals the larger bucket.	Easy2	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Chicken Dance Gomgomi Ims 2Given N gifticons with remaining validity written as D-x, count how many have x of 90 or less.	Easy2	ImplementationString	No attempts yet	1s	1024 MB	Judgeable
Redistributing the Setting FeesGiven each setter's fee and the amounts they hand to others, compute the final money of all N+M staff members.	Easy2	ArrayImplementation	No attempts yet	1s	256 MB	Judgeable
Identify, Sort, Index, SolveGiven N problem titles with numbers and difficulties, sort them by number and output the uppercased D-th character of each title in that order.	Easy2	SortingImplementation+1	No attempts yet	1s	512 MB	Judgeable
HCPC 2022 Problem SettingGiven the fee for each difficulty from 1 to 5, find the maximum total fee under two limits on the weighted sum of chosen problems.	Easy2	Brute forceImplementation	No attempts yet	1s	512 MB	Judgeable
Finding Maximal Non-Trivial MonotonesGiven a string of a and b characters, count the a characters that lie in maximal runs of equal letters with length at least 2.	Easy2	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
Mentors and MenteesSort mentor-mentee pairs by mentor in dictionary order, and break ties by mentee in reverse dictionary order.	Easy2	SortingString	No attempts yet	2s	256 MB	Judgeable
Vowel CountFor each lowercase name, print the name, then 1 if it has more vowels (aeiou) than consonants, otherwise 0.	Easy2	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
Soccer StandingsGiven each team's games played and points, list every win-tie-loss record that produces those points, sorted by wins in descending order.	Easy2	Brute forceImplementation	No attempts yet	1s	1024 MB	Judgeable
Buying in BulkGiven item count c and unit price p for each customer, compute the total cost when every item after the first gets a $2 discount.	Easy2	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
Are We Stopping Again?Given the trip length and the gas and food intervals in miles, count the stops made before the destination, with a shared mile counted once.	Easy2	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Fold the Paper NicelyGiven a rectangle and a fold count, each fold halves the longer side with integer division, and the task asks for the final dimensions.	Easy2	SimulationImplementation	No attempts yet	1s	1024 MB	Judgeable
Good Coin DenominationChecks whether each coin in a sorted list of denominations is at least twice the coin before it.	Easy2	ArrayImplementation	No attempts yet	1s	1024 MB	Judgeable
XOGiven the first N moves of a tic-tac-toe game, decide whether X or O moves next, whether X or O has won, or whether the game is a draw.	Easy2	ImplementationSimulation	No attempts yet	1s	1024 MB	Judgeable
WalktoberFor each day, find the highest step count among all participants, then sum how far John's last-year steps fall short of that maximum.	Easy2	ArrayImplementation	No attempts yet	Not set	1024 MB	Judgeable
CurlingCount each team's stones that touch the house and are closer to the center than every opposing stone that also touches it.	Easy2	ImplementationMath	No attempts yet	20s	1024 MB	Judgeable
Big NumberGiven a positive integer, the task prints each digit as a 4-row block drawn from a fixed font, with a blank line between digits.	Easy2	ImplementationString	No attempts yet	1s	1024 MB	Judgeable
SnowflakesFor each k by k grid of digits, decide whether it is Beautiful, Graceful, Magnificent, or Useless based on its mirror symmetry.	Easy2	ImplementationArray	No attempts yet	1s	1024 MB	Judgeable
V for VendettaPrint a V shape made of stars for each input N, with the arms growing in size as N increases.	Easy2	ImplementationSimulation	No attempts yet	1s	1024 MB	Judgeable
Continuous?Given two linear pieces split at x=k, determine whether the function is continuous at k, and print f(k) if it is.	Easy2	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Limit of a Sequence RatioGiven a_1, a_2 and the recurrence a_i = ba_(i-1) + ca_(i-2), find the limit of a_n / a_(n-1) as n grows without bound.	Easy2	Math	No attempts yet	1s	1024 MB	Judgeable
ReverseGiven several strings with indices i and j, print each string with the characters from index i up to j-1 removed.	Easy2	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
SquareGiven words, print a square where each row is the word cyclically shifted one more position than the row above it.	Easy2	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
QuadraticsFor each data set, read the coefficients a, b, c of a quadratic equation and print both real roots rounded to the thousandths place.	Easy2	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
OrnamentsGiven the number of layers, find the total ornaments in a triangular pyramid where layer k holds k(k+1)/2 balls.	Easy2	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
ZeroGiven a zero-free integer k, find the next positive integer after k that also contains no zero digit.	Easy2	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
DrawGiven shape names, sizes, and a filled or empty flag for each data set, print the shape as ASCII art made of # characters.	Easy2	Implementation	No attempts yet	1s	1024 MB	Judgeable
FriendsGiven several datasets of friends, each with a like score, print the names sorted from highest score to lowest.	Easy2	SortingImplementation	No attempts yet	1s	1024 MB	Judgeable
PresidentsRead n lines of president last names, map each name to its bill value, and output the total dollar amount in the wallet.	Easy2	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
Time LimitsFor each dataset, find the smallest whole-second time limit that is at least s times the slowest model solution's time in milliseconds.	Easy2	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
DateConvert each Month Day, Year date to MM/DD/YY, printing Invalid when the month name is misspelled or the day is outside 1 to 31.	Easy2	ImplementationString	No attempts yet	1s	1024 MB	Judgeable
BombGiven a grid of walls, empty cells, and enemies, find the empty cell where a bomb destroys the most enemies along four directions, stopped by walls.	Easy2	MatrixSimulation	No attempts yet	1s	1024 MB	Judgeable
ScaleFor each line of space-separated integers, output a new list where every value is multiplied by its neighboring values.	Easy2	ArrayImplementation	No attempts yet	1s	1024 MB	Judgeable
PlaytimeConverts each game's minutes played into years (365 days), days, hours, and minutes, printing only the units greater than 0.	Easy2	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
Floor CleanerGiven a 10 by 10 floor grid and a list of obstruction coordinates, print the locations the robot could not clean, sorted by row then column.	Easy2	ImplementationSorting	No attempts yet	1s	1024 MB	Judgeable
PalindromeRead a lowercase word of unknown or known length and print TAK if it is a palindrome, otherwise NIE, using little memory.	Easy2	Two pointersString	No attempts yet	5s	4 MB	Judgeable
Growth Potion Selection TicketGiven a character level from 200 to 239, the task is to pick the Growth Potion that lets the character reach the highest level, with ties going to the lower potion.	Easy2	ImplementationBrute force	No attempts yet	1s	1024 MB	Judgeable
Choosing ProblemsGiven the slot each idea fits, decide whether every one of the fifteen slots can be filled, with slots 5A, 5B, and 5C each needing two problems.	Easy2	Hash mapImplementation	No attempts yet	1s	1024 MB	Judgeable
A+BGiven two positive integers a and b with at most 5000 digits each, print their sum.	Easy2	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
FarmGiven the total heads X and legs Y of hens (2 legs each) and cows (4 legs each), find how many hens and cows there are.	Easy2	MathImplementation	No attempts yet	0.15s	1024 MB	Judgeable
OczkoGiven each player's card string, find the players who reach the highest score not exceeding 21, counting each Ace as 1 or 11.	Easy2	ImplementationString	No attempts yet	2s	1024 MB	Judgeable
Horizontal HeartsPrint N ASCII hearts made of at signs, placed side by side with exactly one space between each pair.	Easy2	ImplementationString	No attempts yet	5s	1024 MB	Judgeable
Alternating wordGiven a string, find the fewest letters to delete so that no two adjacent remaining letters are equal.	Easy2	StringGreedy	No attempts yet	4s	1024 MB	Judgeable
Non Classical ProblemGiven N fractions a_i/b_i, find the minimum, the maximum, and the sum of the values.	Easy2	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
New TimeGiven the clock's time and the correct time, find the fewest presses of a +1 minute button and a +1 hour button needed to match them.	Easy2	Brute forceMath+1	No attempts yet	2s	1024 MB	Judgeable
Kent-buggenGiven n artist names, count how many distinct names appear more than once.	Easy2	Hash mapString	No attempts yet	6s	1024 MB	Judgeable
Sum of a SequenceGiven N and a minimum length L, find the shortest run of consecutive non-negative integers summing to N, or print -1 if none exists within length 100.	Easy3	MathBrute force+1	No attempts yet	2s	128 MB	Judgeable
TreasureGiven two arrays A and B, rearrange A (B stays fixed) to minimize the sum of elementwise products, using the sorted pairing strategy.	Easy3	GreedySorting+1	No attempts yet	2s	128 MB	Judgeable
DivisorsGiven all proper divisors of an unknown number N, compute N using the fact that the smallest and largest proper divisors multiply to N.	Easy3	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
LiesUsing union-find on party attendees, determine which parties can be exaggerated without conflicting with people who must always hear the truth.	Easy3	Union-findGraph+1	No attempts yet	2s	128 MB	Judgeable
Guitar StringsBuy at least N guitar strings using packages of 6 or single strings from M brands at given prices, minimizing total cost.	Easy3	Brute forceGreedy+1	No attempts yet	2s	128 MB	Judgeable
Number SquareGiven an N by M grid of digits, find the area of the largest axis-aligned square whose four corner cells share the same digit.	Easy3	Brute forceMatrix+1	No attempts yet	2s	128 MB	Judgeable
Tournament Meeting RoundSimulate a single-elimination tournament where positions are halved each round to find when two specific players first face each other.	Easy3	SimulationMath+1	No attempts yet	1s	512 MB	Judgeable
FriendsGiven an N x N friendship matrix (N ≤ 50), find the maximum count of people reachable within two friendship links from any single person.	Easy3	GraphMatrix+1	No attempts yet	2s	128 MB	Judgeable
KingMove a king on an 8x8 board by given commands; if it lands on the stone, the stone slides one square the same way unless it would leave the board.	Easy3	SimulationImplementation	No attempts yet	2s	128 MB	Judgeable
Leaf Nodes in a TreeGiven a tree by parent array, delete a node and all its descendants, then count how many leaf nodes remain.	Easy3	TreeDFS+1	No attempts yet	2s	128 MB	Judgeable
ZGiven N and coordinates (r,c) in a 2^N x 2^N grid, compute the visit order index of that cell under recursive Z-order (Morton order) traversal.	Easy3	Divide and conquerRecursion+1	No attempts yet	0.5s	512 MB	Judgeable
Addition CycleSimulate a digit-transformation cycle on a two-digit number until it returns to the original value and count the steps.	Easy3	SimulationMath	No attempts yet	2s	128 MB	Judgeable
Minimum String DifferenceSlide the shorter string A across every possible alignment position over B and output the minimum number of mismatched characters.	Easy3	StringSliding window+1	No attempts yet	2s	128 MB	Judgeable
UnderprimeCount integers in a range whose total number of prime factors (with multiplicity) is itself a prime number.	Easy3	Number theoryMath+1	No attempts yet	2s	128 MB	Judgeable
Least Common Multiple of at Least Three NumbersGiven five distinct positive integers up to 100, find the smallest number divisible by at least three of them, essentially the minimum LCM over all triples.	Easy3	MathBrute force+2	No attempts yet	2s	128 MB	Judgeable
RGB StreetGiven per-house costs for three colors, compute the minimum total cost to paint all houses in a line so that no two adjacent houses share a color.	Easy3	Dynamic programmingArray	No attempts yet	0.5s	128 MB	Judgeable
Josephus PermutationSimulate the Josephus elimination order for N people counting off every K-th person in a circle and print the removal sequence.	Easy3	QueueSimulation+1	No attempts yet	2s	256 MB	Judgeable
Come Back HomeCount simple paths of exact length K from the bottom-left to the top-right cell of a small grid, avoiding blocked cells and revisits.	Easy3	BacktrackingDFS+1	No attempts yet	2s	128 MB	Judgeable
Finding the RankGiven a sorted list of scores with a capacity limit, compute the rank of a new score or return -1 if the list is full and the score is not higher than the last entry.	Easy3	ArrayImplementation+1	No attempts yet	2s	128 MB	Judgeable
Strange MultiplicationGiven two large numbers as digit strings, compute the sum of all pairwise products of their digits, which equals the product of their digit sums.	Easy3	MathString+1	No attempts yet	2s	256 MB	Judgeable
Dice SumGiven three dice with sizes S1, S2, S3, find the sum value that occurs most often among all possible triples, choosing the smallest if tied.	Easy3	Brute forceMath+1	No attempts yet	2s	128 MB	Judgeable
Student NumbersGiven N equal-length numeric strings, find the smallest suffix length k so that all suffixes of length k remain distinct.	Easy3	StringBrute force+1	No attempts yet	2s	128 MB	Judgeable
Castle GuardsGiven a grid of guards, compute the minimum number of guards to add so every row and column has at least one, which equals the max of empty-row count and empty-column count.	Easy3	ArrayGreedy+1	No attempts yet	2s	128 MB	Judgeable
Switches On and OffSimulate switch toggles where male students flip every multiple of their number and female students flip the largest symmetric interval centered on their number.	Easy3	SimulationArray+2	No attempts yet	2s	128 MB	Judgeable
Binary AdditionAdd two binary strings up to 80 digits long and print the sum in binary without leading zeros.	Easy3	StringMath+1	No attempts yet	2s	128 MB	Judgeable
Make a PalindromeGiven a lowercase string of length at most 50, find the minimum length of a palindrome obtained by appending characters only to its end.	Easy3	StringBrute force+1	No attempts yet	2s	128 MB	Judgeable
DFS and BFSGiven an undirected graph, output the vertex visit order for DFS then BFS starting from a given vertex, always preferring the smallest-numbered neighbor.	Easy3	DFSBFS+1	No attempts yet	2s	128 MB	Judgeable
Alphabet DiamondGiven a repeating diamond-pattern tile defined by N, print the characters inside a specified rectangular region of the infinite tiled plane.	Easy3	SimulationMath+1	No attempts yet	2s	128 MB	Judgeable
Symmetric DifferenceGiven two sets of natural numbers, compute the size of their symmetric difference.	Easy3	Hash mapArray+1	No attempts yet	2s	256 MB	Judgeable
War - Land GrabFor each region's list of soldier army IDs, find the majority element that appears more than half the time, or print SYJKGW if none exists.	Easy3	ArrayHash map	No attempts yet	10s	512 MB	Judgeable
Shortcut Key AssignmentAssign each menu option an unused shortcut letter by checking word-initial letters first, then any letter in the string, following the options in order.	Easy3	SimulationString+1	No attempts yet	2s	128 MB	Judgeable
Lee-myeon and Im-hyeonClassify a number 1 to 2700 as Lee-myeon and/or Im-hyeon based on digit sum parity and prime factorization rules, then output one of four codes.	Easy3	Number theoryImplementation+1	No attempts yet	2s	128 MB	Judgeable
BestsellerGiven N book titles sold in a day, find the most frequent title, breaking ties by lexicographically smallest.	Easy3	Hash mapSorting+1	No attempts yet	2s	128 MB	Judgeable
D-DayCompute the number of days between two calendar dates accounting for leap years, printing 'gg' if the gap reaches 1000 years or more.	Easy3	MathImplementation	No attempts yet	2s	128 MB	Judgeable
Decimal DigitSimulate long division of A by B to output the N-th digit after the decimal point.	Easy3	SimulationMath+1	No attempts yet	2s	128 MB	Judgeable
Knight TourCheck whether a given sequence of 36 squares on a 6x6 board forms a valid closed knight's tour with legal moves between consecutive squares and back to the start.	Easy3	SimulationArray+1	No attempts yet	2s	128 MB	Judgeable
Missed CallSimulate an album of N songs with 5-second gaps and a phone ringing every D seconds to find the first ring Kangto can actually hear.	Easy3	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
Arithmetic ProgressionGiven a sequence S and starting value A0, find the smallest common difference d >= 0 of an arithmetic progression so that floor(A0+(i+1)d) equals S_i for every index.	Easy3	MathImplementation	No attempts yet	2s	128 MB	Judgeable
Maze ConstructionSimulate a sequence of forward moves and turns on a grid, then print the smallest rectangular map marking visited cells as passable and the rest as walls.	Easy3	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
HockeyCount how many given points lie inside or on the boundary of a stadium shape formed by a rectangle and two semicircular ends.	Easy3	GeometryImplementation	No attempts yet	2s	128 MB	Judgeable
LotteryGiven N, M, K, compute the probability that two random M-subsets of 1..N share at least K numbers using the hypergeometric distribution.	Easy3	CombinatoricsMath+1	No attempts yet	2s	128 MB	Judgeable
Binary to Octal ConversionConvert a binary number with up to 1,000,000 digits into its octal representation.	Easy3	Bit manipulationMath+2	No attempts yet	1s	128 MB	Judgeable
MessagesGiven sheets of names passed around a circle with P/N marks, find who wrote each hurtful (N) message and about whom.	Easy3	SimulationArray+2	No attempts yet	1s	128 MB	Judgeable
Six Degrees of Kevin BaconGiven an unweighted friendship graph, find the vertex whose sum of shortest distances to all others is minimal, breaking ties by smallest index.	Easy3	BFSGraph+1	No attempts yet	2s	128 MB	Judgeable
Eumha Railway 998Find the point on the train's straight-line path where it comes closest to a given station, guaranteed to have integer coordinates.	Easy3	GeometryMath	No attempts yet	2s	128 MB	Judgeable
K-Sejun NumbersCount integers from 1 to N whose every prime factor is at most K, given N up to 100000 and K up to 100.	Easy3	MathNumber theory+1	No attempts yet	2s	128 MB	Judgeable
Serial NumbersSort serial numbers by length, then digit-sum, then a custom lexicographic rule where digits precede letters.	Easy3	SortingString+1	No attempts yet	2s	128 MB	Judgeable
Repairing Pipe LeaksGiven leak positions and a fixed tape length, compute the minimum number of length-L tapes needed so each leak is covered with at least 0.5 margin on both sides.	Easy3	GreedySorting+1	No attempts yet	2s	128 MB	Judgeable
WalkingCompute the minimum time to walk from (0,0) to (X,Y) on a grid where straight moves cost W and diagonal moves cost S.	Easy3	MathGreedy	No attempts yet	2s	128 MB	Judgeable