Strings and text

Parsing, matching, and tries

Under construction

Still being built. Things may change

Total results3,615 problems

Dragon Pattern
Hard9
String matching, Recursion+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Expression and Substring
Hard9
Shortest path, Graph+1
No attempts yet
Time limit
10s
Memory limit
256 MB
Judgeable
Same Suffix Array
Hard9
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Dictionary Survey
Hard9
Trie, Math+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Counting Distinct Suffix Arrays
Hard9
Combinatorics, String+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Counting Strings
Hard9
Dynamic programming, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Binary cryptarithm decryption
Hard9
Backtracking, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bracket Substrings
Hard9
String, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
XOR Queries
Hard9
Trie, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hacker
Hard9
Segment tree, Hash map+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Distinct Substring Queries
Hard9
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Incremental Double Free Strings
Hard9
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tarot Sham Boast
Hard9
String matching, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pseudoknot
Hard9
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Intuidiff
Hard9
String matching, Greedy+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Crazy Rotations
Hard9
String matching, Combinatorics+2
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
Kabobs
Hard9
Dynamic programming, String+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Want to solve a problem?
Hard9
String matching, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Banner
Hard9
String, Dynamic programming+1
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
LISA
Hard9
Trie, String+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
AB-Strings
Hard9
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
mex
Hard9
Bit manipulation, Trie+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Message
Hard9
Dynamic programming, String matching+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Beautiful Manyeongro
Hard9
Trie, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Parameterized Pattern Matching
Hard9
String, String matching+2
No attempts yet
Time limit
Not set
Memory limit
16 MB
Judgeable
Mischievous Junseok
Hard9
Brute force, Recursion+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Sequence and Queries 34
Hard9
String matching, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lengths and Periods
Hard9
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kontakt for Two
Hard9
Trie, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gnalcats
Hard9
String, Stack+2
No attempts yet
Time limit
0.3s
Memory limit
512 MB
Judgeable
Pilgrim's Memories and the Impressed God
Hard9
Dynamic programming, String+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Speed Reading Course
Hard9
Number theory, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Knowledge
Hard9
String, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bitwise Xor
Hard9
Bit manipulation, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Grammarly
Hard9
String, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Algorithm
Hard9
String, Hash map+2
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
Counting Edit Distances
Hard9
Dynamic programming, String+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Humongous String
Hard9
String, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Play Games with Rounddog
Hard9
String, String matching+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Magic Strings
Hard9
Dynamic programming, Matrix+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Integer Equation Checker
Hard9
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Alice and Bob (and string): Double Menace
Hard9
Game theory, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lyndon Substring
Hard9
String, String matching+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Addition
Hard9
String matching, Simulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Rikka with String
Hard9
String, String matching+1
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Doublindromes
Hard9
String, String matching+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
New Divide
Hard9
Bit manipulation, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Long Binary Sequence
Hard9
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Aho
Hard9
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Joke
Hard9
String matching, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Game
Hard9
Game theory, Dynamic programming+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Prefix-free Queries
Hard9
String, Trie+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Flip a Coin
Hard9
Probability, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
K-th String
Hard9
String, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Palindrome
Hard9
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Inversions in Lexicographical Order
Hard9
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Suffix Array for Thue-Morse
Hard9
Array, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Generator
Hard9
Probability, String matching+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Jong Hyok and String
Hard9
String, Trie+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Right Expansion Of The Mind
Hard9
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
DNA Decoding
Hard9
Trie, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Oleg and Binary Sequences
Hard9
String matching, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Anti-hash Test
Hard9
String matching, Recursion+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fibonacci Suffix Array
Hard9
String, Recursion+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hamming Distance
Hard9
Divide and conquer, String matching+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Boring Lesson
Hard9
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Back to Space
Hard9
String matching, Hash map+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Deque Game
Hard9
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Common Bracket Dictionary
Hard9
String matching, String+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Carpenters' Language
Hard9
String, Stack+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Game of the Retired
Hard9
Game theory, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Master of String Manipulation
Hard9
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Crab's Cannon
Hard9
String, String matching+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Magic Box
Hard9
String matching, String+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Minimal Cyclic Shift
Hard9
String, Number theory+2
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Nondeterministic Finite Automaton
Hard9
Graph, Number theory+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Gene Folding
Hard9
String, String matching+2
No attempts yet
Time limit
5s
Memory limit
2048 MB
Judgeable
Ternary String Revolution
Hard9
String, Math+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
String Theory
Hard9
String, String matching+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Recursive String
Hard9
String, Recursion+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stock Price Prediction
Hard9
String matching, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Heretical Möbius
Hard9
Number theory, String matching+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Philosophical Balance
Hard9
String, Game theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tearing Barcodes
Hard9
String, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sgame
Hard9
String, Sorting+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Uniform String
Hard9
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
First Occurrence
Hard9
String matching, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindromi
Hard9
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Transmitter
Hard9
String matching, Two pointers+2
No attempts yet
Time limit
3s
Memory limit
1536 MB
Judgeable
Fibonacci Products
Hard9
Dynamic programming, String+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Tekstówka
Hard9
Dynamic programming, String+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Great Thermion Collider
Hard9
Dynamic programming, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Score Betting
Hard9
Trie, String matching+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Signs on the Road
Hard9
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Game with a tree
Hard9
Trie, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Max and Duke
Hard9
String, String matching+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Very Strange String
Hard9
String matching, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fibonacci Digit Count
Hard9
Math, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Machine Learning
Hard9
Backtracking, Trie+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Two Sequences
Hard9
String, Greedy+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Dragon PatternCount how many times pattern S appears as a contiguous block in the length 2^n direction string of the order-n left dragon curve.	Hard9	String matchingRecursion+2	No attempts yet	5s	128 MB	Judgeable
Expression and SubstringFind the shortest string that matches the given regular expression and contains S as a substring, breaking ties by lexicographic order.	Hard9	Shortest pathGraph+1	No attempts yet	10s	256 MB	Judgeable
Same Suffix ArrayCount the strings that differ from the given length N string in exactly one position and keep the same suffix array.	Hard9	StringString matching+1	No attempts yet	2s	256 MB	Judgeable
Dictionary SurveyFind how many leading pages of the integers from A to B in lexicographic order pin down both A and B.	Hard9	TrieMath+1	No attempts yet	3s	256 MB	Judgeable
Counting Distinct Suffix ArraysCount how many distinct suffix arrays length-N strings with at most M distinct letters produce, modulo 1e9+7.	Hard9	CombinatoricsString+1	No attempts yet	1s	512 MB	Judgeable
Counting StringsCount strings over the lowercase alphabet whose length lies between LK and LK+N and in which at most K non-overlapping copies of a given pattern S can be found.	Hard9	Dynamic programmingString matching+2	No attempts yet	2s	512 MB	Judgeable
Binary cryptarithm decryptionGiven a short cipher string where letters replace some characters of an unknown binary equation, count how many valid equations from the given grammar match it.	Hard9	BacktrackingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Bracket SubstringsCount how many distinct balanced bracket sequences appear as non-empty substrings of a given bracket string of length up to 500,000.	Hard9	StringHash map+2	No attempts yet	2s	512 MB	Judgeable
XOR QueriesMaintain an array under appends, rollbacks of the last k elements, and range queries for max XOR, count <= x, and k-th smallest.	Hard9	TrieSegment tree+2	No attempts yet	2s	512 MB	Judgeable
HackerSimulate substring comparisons, substring copy from a fixed string, and range letter-increment operations on a mutable string of length N.	Hard9	Segment treeHash map+2	No attempts yet	4s	512 MB	Judgeable
Distinct Substring QueriesMaintain a string under push-back and pop-front operations, reporting the number of distinct substrings after each of up to a million queries.	Hard9	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Incremental Double Free StringsFind the nth string of length k(k+1)/2 that uses one letter j times for each j up to k and has no two equal adjacent letters, in alphabetical order.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Tarot Sham BoastGiven up to 10 equal-length strings over {R,P,S} and a length n random string, sort the strings by the probability each occurs as a contiguous block.	Hard9	String matchingProbability+2	No attempts yet	2s	512 MB	Judgeable
PseudoknotFind the largest t such that the string splits into u v z^R u^R y z with \|u\|>=t and \|z\|>=t, or report -1 if no such split exists.	Hard9	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
IntuidiffFind the minimum number of blocks, each a substring of the first string or a single new character, whose concatenation equals the second string.	Hard9	String matchingGreedy+2	No attempts yet	7s	512 MB	Judgeable
Crazy RotationsGiven a row of coloured lights, find the smallest rotation amount that can appear at position p in a non-decreasing sequence of rotation craziness values.	Hard9	String matchingCombinatorics+2	No attempts yet	15s	512 MB	Judgeable
KabobsCount length-K strings over the given alphabet that satisfy all substring-implication rules of the form b>e, modulo 10^7.	Hard9	Dynamic programmingString+2	No attempts yet	5s	512 MB	Judgeable
Want to solve a problem?For given K and C, choose A > 0 to maximize the characters saved by writing K+A repeated K+A times instead of K repeated K times, minus C times A.	Hard9	String matchingMath+2	No attempts yet	1s	128 MB	Judgeable
BannerCount the orders of the 26 machines that let greedy longest-substring sewing finish a string of up to 35 letters in the fewest hours, modulo four primes.	Hard9	StringDynamic programming+1	No attempts yet	6s	512 MB	Judgeable
LISAGiven n strings and range queries, count distinct concatenations of a non-empty prefix of one string in the range with a non-empty suffix of another string in the range.	Hard9	TrieString+2	No attempts yet	3s	512 MB	Judgeable
AB-StringsGiven two strings of a and b, swap prefixes between them with the fewest operations so one string is all a and the other is all b.	Hard9	GreedyString+1	No attempts yet	1s	512 MB	Judgeable
mexAfter XORing every element of a sequence with each query value x, report the mex (smallest missing non-negative integer) of the sequence.	Hard9	Bit manipulationTrie+2	No attempts yet	1s	512 MB	Judgeable
MessageCount length-n lowercase strings that contain a given pattern p as a substring, modulo m, where n can reach 10^12 and p has length at most 50.	Hard9	Dynamic programmingString matching+2	No attempts yet	5s	512 MB	Judgeable
Beautiful ManyeongroCount directed paths in a rooted tree whose edge-label string equals a given pattern P.	Hard9	TrieDFS+2	No attempts yet	2s	512 MB	Judgeable
Parameterized Pattern MatchingFind every substring of text T that p-matches pattern P, where parameter names must correspond under a bijection and tokens match exactly.	Hard9	StringString matching+2	No attempts yet	Not set	16 MB	Judgeable
Mischievous JunseokGiven a short English word and a multiset of letters, count the distinct strings obtainable from any contiguous substring with that letter multiset under the recursive half-split-and-reverse rule.	Hard9	Brute forceRecursion+2	No attempts yet	2s	256 MB	Judgeable
Sequence and Queries 34Maintain two integer sequences under updates and range queries: for a suffix of a compute the longest match against b and how many suffixes achieve it, compare suffixes of b, and test whether a concatenation of two b-substrings is itself a substring of b.	Hard9	String matchingSegment tree+2	No attempts yet	2s	512 MB	Judgeable
Lengths and PeriodsGiven a string of up to 200,000 lowercase letters, find its critical exponent, the largest repetition ratio of a substring, printed as an irreducible fraction.	Hard9	StringString matching+1	No attempts yet	2s	512 MB	Judgeable
Kontakt for TwoGiven a dictionary and queries of (secret word, K), find the maximum number of words the guesser can name before the game ends.	Hard9	TrieTree+2	No attempts yet	2s	512 MB	Judgeable
GnalcatsDecide whether two genes, each a sequence of seven possible base transformations on proteins, produce identical results or both fail on every sufficiently long input protein.	Hard9	StringStack+2	No attempts yet	0.3s	512 MB	Judgeable
Pilgrim's Memories and the Impressed GodGiven an N by N grid of 0 and 1 trials, sum X^2+1 over every distinct color string formed by monotone chains of sites, where X counts how often that string occurs.	Hard9	Dynamic programmingString+1	No attempts yet	8s	1024 MB	Judgeable
Speed Reading CourseCount how many positions i where c contains the given m-bit word w, with c defined by an arithmetic progression modulo n against threshold p.	Hard9	Number theoryString matching+2	No attempts yet	2s	512 MB	Judgeable
KnowledgeCount strings of length x reachable from s by inserting or deleting the blocks aa, bbb, and ababab, modulo 998244353.	Hard9	StringCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Bitwise XorCount non-empty subsequences in which the pairwise xor of every two chosen elements is at least x, modulo 998244353.	Hard9	Bit manipulationTrie+2	No attempts yet	2s	512 MB	Judgeable
GrammarlyGiven a string up to 300,000 characters, count simple paths from the whole string through distinct substrings where each step deletes one character, modulo 998244353.	Hard9	StringDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
String AlgorithmFor every k, cut s into blocks of length k, discard the tail, and count block pairs whose Hamming distance is at most one.	Hard9	StringHash map+2	No attempts yet	20s	512 MB	Judgeable
Counting Edit DistancesCount the number of distinct strings over 'A' to 'Z' whose Levenshtein distance from a given string s is exactly d, modulo 998244353.	Hard9	Dynamic programmingString+2	No attempts yet	10s	512 MB	Judgeable
Humongous StringGiven n and k, count the distinct non-empty substrings of the length-n prefix of the infinite string S built by concatenating the growing blocks T_i.	Hard9	StringMath+1	No attempts yet	1s	512 MB	Judgeable
Play Games with RounddogFor each query substring T, find the largest total stone count of Calabash's piles such that he wins Nim no matter which piles Rounddog removes, or -1.	Hard9	StringString matching+2	No attempts yet	5s	512 MB	Judgeable
Magic StringsGiven n up to 10^18, count the distinct subsequences of the recursively doubled string F_n modulo 10^9+7 for up to 10 test cases.	Hard9	Dynamic programmingMatrix+2	No attempts yet	4s	512 MB	Judgeable
Integer Equation CheckerClassify an equation string as correct, format error, math error, or a typo fixable by replacing at most two characters with a valid correct equation.	Hard9	Brute forceImplementation+2	No attempts yet	1s	512 MB	Judgeable
Alice and Bob (and string): Double MenaceGiven string s and k, find the k-th lexicographically smallest substring t of s from which Alice wins the two-sided extension game, or report that fewer than k exist.	Hard9	Game theoryString matching+1	No attempts yet	2s	512 MB	Judgeable
Lyndon SubstringFor each query (i, j), find the length of the longest Lyndon substring of the concatenation s_i s_j, given n strings and m queries.	Hard9	StringString matching+1	No attempts yet	3s	256 MB	Judgeable
AdditionDesign a short string-rewriting script in a custom language that reads two binary numbers joined by + and rewrites them into their binary sum.	Hard9	String matchingSimulation+2	No attempts yet	1s	256 MB	Judgeable
Rikka with StringGiven a string over the letters a to l, decide for each suffix whether some permutation of the 12 letters can make that suffix the lexicographically largest suffix.	Hard9	StringString matching+1	No attempts yet	6s	512 MB	Judgeable
DoublindromesCount distinct substrings of s that are palindromes and split into two non-empty palindromes, with length at least k.	Hard9	StringString matching+2	No attempts yet	3s	512 MB	Judgeable
New DivideFor every prefix of the array, split it into two contiguous parts maximizing the sum of the two parts' XOR values.	Hard9	Bit manipulationTrie+2	No attempts yet	2s	512 MB	Judgeable
Long Binary SequenceCount the distinct consecutive substrings of a binary string of length up to 1e9, where the 1s are given at m up to 1000 positions.	Hard9	String matchingString+1	No attempts yet	2s	512 MB	Judgeable
AhoAfter each character appended to hidden T, ask at most five equality queries, then report how many substrings of T equal hidden S.	Hard9	StringString matching+1	No attempts yet	1s	512 MB	Judgeable
JokeGiven a text and up to ten patterns with per-letter erasure costs, delete letters so that no pattern occurs, minimizing total cost.	Hard9	String matchingDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
GamePlayers alternately remove an end element from a sequence, and the mover who reaches a terminal sequence wins. Decide whether the first player, the second, or neither wins.	Hard9	Game theoryDynamic programming+1	No attempts yet	8s	512 MB	Judgeable
Prefix-free QueriesGiven a string and queries of substring lists, count the prefix-free subsets of the substrings modulo m, for each query.	Hard9	StringTrie+2	No attempts yet	2s	256 MB	Judgeable
Flip a CoinTwo players each pick a heads/tails string of length up to 20; a fair coin is flipped until one or both strings appear, and we must output the probabilities of Alice winning, Bob winning, and a tie.	Hard9	ProbabilityDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
K-th StringCount permutations t of n distinct letters whose k-th smallest non-empty substring equals s, modulo 1e9+7.	Hard9	StringCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
PalindromeGiven a string s, each query concatenates the length-l substrings starting at the listed positions and asks for the number of palindromic substrings of the result.	Hard9	StringString matching+1	No attempts yet	2s	512 MB	Judgeable
Inversions in Lexicographical OrderGiven n with up to 250000 digits, count the inversions in the permutation formed by sorting 1 to n as strings.	Hard9	CombinatoricsDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Suffix Array for Thue-MorseGiven the order k of a Thue-Morse string of length 2^k, answer q queries for suf[p], the suffix array entries, with k up to 60.	Hard9	ArrayString+2	No attempts yet	2s	512 MB	Judgeable
GeneratorFind the expected number of random draws until all n given length-L sequences have each appeared as a contiguous block of the stream.	Hard9	ProbabilityString matching+2	No attempts yet	3s	256 MB	Judgeable
Jong Hyok and StringGiven n pattern strings, for each query string Q count the substrings T of the patterns with the same set of (pattern, end position) occurrence pairs as Q.	Hard9	StringTrie+2	No attempts yet	1s	1024 MB	Judgeable
Right Expansion Of The MindGroup n infinite strings, each formed by a finite prefix s followed by repeats of t, so that within each group every pair is mutually a subsequence of the other; minimize the number of groups.	Hard9	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
DNA DecodingAdd genes to a prefix-free set or append DNA strands, then report which strands become fully decodable for the first time after each operation.	Hard9	TrieString matching+1	No attempts yet	2s	512 MB	Judgeable
Oleg and Binary SequencesCount binary sequences of length n whose Z-function matches the given entries, with -1 marking unknown values, modulo 1e9+7.	Hard9	String matchingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Anti-hash TestCount occurrences of u in the popcount-parity string s(n) of length 2^n, and how many strings v share that occurrence count.	Hard9	String matchingRecursion+1	No attempts yet	1s	256 MB	Judgeable
Fibonacci Suffix ArrayGiven n, q, and m, the task finds the suffix array of the Fibonacci word fib_n at q query positions and prints each value modulo m.	Hard9	StringRecursion+1	No attempts yet	5s	512 MB	Judgeable
Hamming DistanceGiven a sequence a of length n and m, find the minimum and the sum mod 1e9+7 of Hamming distances to every length-n window of S^m.	Hard9	Divide and conquerString matching+1	No attempts yet	3s	512 MB	Judgeable
Boring LessonGiven strings s and t and a list of n favorite strings, find the minimum edit distance from s to t and the largest subset of favorites that can all appear along a shortest edit path, then output that subset in order.	Hard9	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Back to SpaceGiven an r by c grid of colored tiles, find a panel size a by b and a row shift s so that the grid is covered by shifted copies of the panel, with minimal panel area.	Hard9	String matchingHash map+1	No attempts yet	2s	512 MB	Judgeable
Deque GameGiven two starting stacks over a K-letter alphabet, count for each how many distinct L-length stacks contain that starting stack as a contiguous block, and compare the counts.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Common Bracket DictionaryGiven bracket strings A and B and a number K, find the K-th distinct correct bracket sequence in dictionary order that is a substring of both, or print -1.	Hard9	String matchingString+1	No attempts yet	5s	1024 MB	Judgeable
Carpenters' LanguageAfter each of q insertions of a run of '(' or ')' at a given position, decide whether the whole string is a well-formed sentence of the grammar S -> SS \| (S) \| )S( \| epsilon.	Hard9	StringStack+2	No attempts yet	1s	512 MB	Judgeable
Game of the RetiredGiven K grid boards fenced by two non-touching R/D paths, decide who wins the token game where Jeyeon moves right and Deokin moves down.	Hard9	Game theoryString+1	No attempts yet	1s	1024 MB	Judgeable
Master of String ManipulationCount distinct strings reachable from S after exactly M single-letter increments (z stays z), modulo 1e9+7, with N up to 300 and M up to 1e18.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2.5s	1024 MB	Judgeable
Crab's CannonGiven a subset of the palindromic prefix lengths of an unknown string of length l, find the minimum number of palindromic prefixes such a string can have.	Hard9	StringString matching+1	No attempts yet	3s	512 MB	Judgeable
Magic BoxGiven a string, count pairs of intervals that spell the same text, grouped by how many squares the two intervals activate, for each count from 0 to n.	Hard9	String matchingString+1	No attempts yet	5s	512 MB	Judgeable
Minimal Cyclic ShiftGiven n lengths of random lowercase strings, compute the expected number of answers that still match after the answers are written in a shifted order, modulo 998244353.	Hard9	StringNumber theory+2	No attempts yet	1.5s	256 MB	Judgeable
Nondeterministic Finite AutomatonBuild an n-state NFA over 0 and 1 so that the shortest string it cannot recognize is longer than 18 for n=6 and longer than 400 for n=20.	Hard9	GraphNumber theory+1	No attempts yet	1s	256 MB	Judgeable
Gene FoldingGiven a DNA string, repeatedly fold it at a point where the sequence reads the same in both directions, merging matching nucleotides, and report the shortest length reachable.	Hard9	StringString matching+2	No attempts yet	5s	2048 MB	Judgeable
Ternary String RevolutionGiven a rewrite system on ternary strings, count for each query string the substrings of s that can be transformed into it.	Hard9	StringMath+2	No attempts yet	1s	256 MB	Judgeable
String TheoryCount substrings of S that equal some nonempty string repeated exactly k times, counting each occurrence position separately.	Hard9	StringString matching+2	No attempts yet	4s	512 MB	Judgeable
Recursive StringGiven a string T built by recursively wrapping characters around previous blocks, recover the original string S and repetition counts A.	Hard9	StringRecursion+2	No attempts yet	1s	256 MB	Judgeable
Stock Price PredictionFind every start position in y where the length-m window has the same relative-rank pattern (order-isomorphic) as the pattern sequence x.	Hard9	String matchingSorting+2	No attempts yet	1s	1024 MB	Judgeable
Heretical MöbiusGiven a 200-character binary string t, find the first position p where t appears in the sequence \|mu(1)\|, \|mu(2)\|, ... up to 10^9, or report -1.	Hard9	Number theoryString matching+1	No attempts yet	1s	256 MB	Judgeable
Philosophical BalanceGiven a string, choose a probability distribution over its suffixes to maximize the minimum expected LCP against any suffix the guard picks.	Hard9	StringGame theory+2	No attempts yet	1s	256 MB	Judgeable
Tearing BarcodesGiven a long bracket string (a pattern repeated many times) and a second string attached to each purchased drink, find the maximum number of drinks you can buy, where each drink costs K valid-barcode fragments and each purchase yields a new string to tear.	Hard9	StringGreedy+2	No attempts yet	1s	1024 MB	Judgeable
SgameGiven a string and many queries (m, k), find the maximum occurrence count of a substring with length between m and k that cannot be extended to a longer string with the same count.	Hard9	StringSorting+2	No attempts yet	4s	1024 MB	Judgeable
Uniform StringRepeatedly apply a reduction that maps zero-runs to 1 or 0 based on their lengths and count, and report when the string stops being uniform.	Hard9	StringImplementation+2	No attempts yet	1s	1024 MB	Judgeable
First OccurrenceGiven l and r up to 10^18, find the smallest index where the Thue-Morse substring t[l..r] first appears in the sequence.	Hard9	String matchingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
PalindromiEach concatenation joins two binary strings in a given order, and the task asks for the number of distinct palindromic substrings after each join.	Hard9	StringString matching+1	No attempts yet	1s	512 MB	Judgeable
TransmitterCount contiguous blocks of strings whose total pairwise longest common prefix length is at least K.	Hard9	String matchingTwo pointers+2	No attempts yet	3s	1536 MB	Judgeable
Fibonacci ProductsGiven two positive integers in Zeckendorf form, print their product in the same Fibonacci representation. Total input length is up to 10^6 bits.	Hard9	Dynamic programmingString+1	No attempts yet	20s	1024 MB	Judgeable
TekstówkaGiven strings s and t, answer q queries, each asking for the LCS length of a substring of s and a substring of t.	Hard9	Dynamic programmingString+1	No attempts yet	8s	1024 MB	Judgeable
Great Thermion ColliderCount the ways to turn each blue thermion into red or green so that the chain can react down to one thermion, and report this count after each point update.	Hard9	Dynamic programmingSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Score BettingGiven prefix and suffix lists of scored strings with updates, find the max and min total score of any nonempty string over letters and digits.	Hard9	TrieString matching+2	No attempts yet	1s	1024 MB	Judgeable
Signs on the RoadFind the lexicographically smallest digit string written while walking a graph to visit all towns, and the minimum toll for that string.	Hard9	GraphMinimum spanning tree+2	No attempts yet	2s	1024 MB	Judgeable
Game with a treeAfter each action, count the distinct substrings of all root-to-apple words, where apples are added with letters and removed when picked.	Hard9	TrieTree+1	No attempts yet	2s	1024 MB	Judgeable
Max and DukeGiven a string s and m queries [l, r], count the palindromic substrings that lie entirely inside s[l..r] for each query.	Hard9	StringString matching+2	No attempts yet	4s	1024 MB	Judgeable
Very Strange StringGiven k and m, the task is to build a lowercase string of length at most m whose strangeness (the sum of G_i times F_i) equals k.	Hard9	String matchingMath+1	No attempts yet	2s	1024 MB	Judgeable
Fibonacci Digit CountCount occurrences of the substring "11" within the first N characters of the infinite string formed by writing 1, 2, 3, ... in Fibonacci (Zeckendorf) representation.	Hard9	MathDynamic programming+2	No attempts yet	2s	1024 MB	Judgeable
Machine LearningGiven every binary word up to length n marked accept or reject, build a DFA with the fewest states that matches all the marks.	Hard9	BacktrackingTrie+1	No attempts yet	2s	1024 MB	Judgeable
Two SequencesFor each query, find the k-th element of the lexicographically smallest merge of the prefixes A[1..a] and B[1..b].	Hard9	StringGreedy+1	No attempts yet	3s	1024 MB	Judgeable