Strings and text

Parsing, matching, and tries

Under construction

Still being built. Things may change

Total results3,615 problems

Cyclic Shifts
Hard8
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Almost Bobo Number
Hard8
String, Greedy+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
La Vie En Rose
Hard8
String matching, Dynamic programming+2
No attempts yet
Time limit
2.5s
Memory limit
64 MB
Judgeable
Guess the Data Structure
Hard8
Bit manipulation, Trie+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Proper String Problem
Hard8
String, Trie+1
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable
Length String
Hard8
String, Math+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Viruses
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
0.7s
Memory limit
256 MB
Judgeable
Searching for Strings
Hard8
Sliding window, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Swapping Seats
Hard8
Greedy, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Processing
Hard8
Divide and conquer, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Heavy Burger
Hard8
Segment tree, String matching+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Garland
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Idea Search
Hard8
String matching, String+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Painting Squares
Hard8
String, Combinatorics+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
LCS 8
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Bit String
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Nunchucks Shop
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bidirectional Code
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pipe Inspection
Hard8
Tree, String matching+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Vlak
Hard8
Trie, Game theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Strange Strings
Hard8
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hardcore String Counting 2
Hard8
String, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Necklace Construction
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequence and Queries 40
Hard8
String, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maze Construction
Hard8
Graph, String+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
XOR Data Structure
Hard8
Trie, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Edit Distance Yet Again
Hard8
String, Dynamic programming+1
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
Baby's First Suffix Array Problem
Hard8
String, String matching+1
No attempts yet
Time limit
14s
Memory limit
512 MB
Judgeable
Fibonacci Strings
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Messy kangaroo babies
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Decompression
Hard8
String, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dice Password Security
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Almost Prefix-Free Codes
Hard8
Trie, Tree+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Document Formatting
Hard8
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Names
Hard8
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Robot Assembler
Hard8
String, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Native Expanses
Hard8
String, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Moscow Numbers
Hard8
String, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
«Abracadabra»
Hard8
String, Hash map+2
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Another Substring Query Problem
Hard8
String matching, String+2
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
File Manager
Hard8
Shortest path, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ancient Machine
Hard8
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Mutant Vaccine
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Suffixes may Contain Prefixes
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Removal
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cipher Key
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Text Editor
Hard8
Segment tree, Stack+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Label
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Viruses
Hard8
Dynamic programming, Trie+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Repeats
Hard8
String, String matching+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
May I Add a Letter?
Hard8
String, String matching+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Longest Common Balanced Substring
Hard8
String matching, Prefix sum+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
String Magic
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Almost Periodic String
Hard8
String, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Substring
Hard8
String, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Common Palindromes
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sakura Poetry
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Adhoc Translation
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Princess, a Cryptanalyst
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Billion Million Thousand
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
The Devil of Gravity
Hard8
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Broken Calculator Game
Hard8
Segment tree, String+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Orange Farm Simulation
Hard8
Tree, Trie+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Orange Leaf's Special Training
Hard8
String matching, Segment tree+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Ketek Counting
Hard8
Dynamic programming, String matching
No attempts yet
Time limit
4s
Memory limit
64 MB
Judgeable
Little LCS
Hard8
Combinatorics, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Limited Correspondence
Hard8
DFS, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
W3W (What 3 Words)
Hard8
String, Trie+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cell Division
Hard8
Dynamic programming, Intervals+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Beautiful Words
Hard8
String matching, Trie+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Listing Passwords
Hard8
Union-find, String+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Balanced Binary String
Hard8
String, Combinatorics+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Longest Lyndon Prefix
Hard8
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Rats
Hard8
String, Graph+2
No attempts yet
Time limit
0.75s
Memory limit
256 MB
Judgeable
Gifted Composer
Hard8
String matching, String
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
What a Horrible and Dreadful Formula
Hard8
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
String Product
Hard8
String, Math+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Balanced Rainbow Sequence
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Square Graph
Hard8
String matching, Union-find+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Filipp Rukhovich
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Valid Parenthesis String
Hard8
Segment tree, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Scrambled Words
Hard8
String matching, Hash map+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Funniest Word Search
Hard8
String matching, Trie+2
No attempts yet
Time limit
240s
Memory limit
1024 MB
Judgeable
One is zero, zero is one
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
One-Dimensional Chess
Hard8
Trie, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Most Equal
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Number of Words
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tomb Hater
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Subprime
Hard8
String matching, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Shortest Missing Subsequences
Hard8
String, Greedy+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Rise and Fall
Hard8
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Substrings and Subsequences
Hard8
String, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
How Many Strings Are Less
Hard8
Trie, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Reversible Compression
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pair Programming
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Colorful Bracket Sequences
Hard8
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Joyful KMP
Hard8
String matching, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Repetitions
Hard8
String matching, Divide and conquer+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Decrypting Zodiac
Hard8
String matching, Math+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
I Herd You Like Ternary Operators
Hard8
String, Stack+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Cyclic ShiftsFor each prefix of a string, find the smallest index of its lexicographically minimal cyclic shift, then sum these indices weighted by powers of 8753 modulo 1000000123.	Hard8	StringString matching+1	No attempts yet	2s	512 MB	Judgeable
Almost Bobo NumberGiven an integer n with up to 5,000,000 digits, find the largest almost bobo number strictly less than n, or report -1 if none exists.	Hard8	StringGreedy+1	No attempts yet	3s	512 MB	Judgeable
La Vie En RoseCount which length-m windows of s can be produced from pattern p by swapping disjoint adjacent pairs that are non-overlapping and strictly separated.	Hard8	String matchingDynamic programming+2	No attempts yet	2.5s	64 MB	Judgeable
Guess the Data StructureMaintain an array that supports appending values, range sum queries, xoring every element with x, and sorting the array.	Hard8	Bit manipulationTrie+2	No attempts yet	5s	256 MB	Judgeable
Proper String ProblemGiven n strings over A, C, G, T where none is a substring of another, sum over all ordered pairs the length of the longest string that is a proper suffix of s_i and a proper prefix of s_j.	Hard8	StringTrie+1	No attempts yet	9s	1024 MB	Judgeable
Length StringGiven a and b, output the length string of length a times 10 to the power b, printing only the first 17 characters when that length is at least 21.	Hard8	StringMath+1	No attempts yet	3s	1024 MB	Judgeable
VirusesFor each gene, check whether every virus it can produce contains an antibody fragment, and if not, give the length of the shortest undetected virus.	Hard8	String matchingDynamic programming+1	No attempts yet	0.7s	256 MB	Judgeable
Searching for StringsCount how many distinct permutations of the needle string N occur as a contiguous substring of the haystack string H.	Hard8	Sliding windowString matching+2	No attempts yet	2s	512 MB	Judgeable
Swapping SeatsGiven a circular string of A, B, C, find the minimum number of seat swaps needed so each letter forms one contiguous block.	Hard8	GreedySliding window+2	No attempts yet	2s	512 MB	Judgeable
String ProcessingDecide whether a recursive split-and-swap program can turn string S into T, and if so output the 2^k - 1 bit program.	Hard8	Divide and conquerString+2	No attempts yet	2s	512 MB	Judgeable
Heavy BurgerMaintain a string of parentheses under range flips, and for each query on a substring report the minimum number of characters to insert so the substring becomes a balanced parenthesis sequence.	Hard8	Segment treeString matching+2	No attempts yet	3s	1024 MB	Judgeable
GarlandDelete elements from a binary string so the remaining string is beautiful (beads left of each 1 equal beads right of it, bounded by neighboring 1s), maximizing length.	Hard8	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Idea SearchGiven blocks that append literal strings or copy earlier substrings of the growing text, count how many times pattern p occurs in the final text.	Hard8	String matchingString+1	No attempts yet	5s	1024 MB	Judgeable
Painting SquaresPaint squares black or white and choose the smallest k so that the color pattern in any window of length k, together with whether it runs off the row, always identifies the window's start.	Hard8	StringCombinatorics+2	No attempts yet	4s	1024 MB	Judgeable
LCS 8Count the length-N uppercase strings T whose LCS with S is at least N minus K, modulo 1e9+7, where K is at most 3.	Hard8	Dynamic programmingString+1	No attempts yet	3s	1024 MB	Judgeable
Bit StringCount bit strings of length n that contain P1 as a substring but avoid P2, modulo 1,000,000,007.	Hard8	Dynamic programmingString matching+2	No attempts yet	1.5s	1024 MB	Judgeable
Nunchucks ShopGiven n and k, find the minimum number of binary strings of length n such that every length-n binary string pair with total k ones can be formed by joining two stored sticks, each usable in either orientation.	Hard8	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Bidirectional CodeGiven n up to 10^18, express it as a sum of at most 10 palindromic numbers and output the count and the palindromes.	Hard8	MathGreedy+2	No attempts yet	1s	512 MB	Judgeable
Pipe InspectionCover every edge of a rooted pipe tree with downward walks that spell given letter patterns, at the minimum total pattern cost.	Hard8	TreeString matching+1	No attempts yet	1s	512 MB	Judgeable
VlakTwo players alternately append letters so the growing word stays a prefix of a word in the mover's own song; decide who wins under optimal play.	Hard8	TrieGame theory+2	No attempts yet	1s	512 MB	Judgeable
Strange StringsGiven a string s, count the number of distinct substrings t such that the set of substrings of t equals the set of subsequences of t.	Hard8	StringHash map+2	No attempts yet	1s	512 MB	Judgeable
Hardcore String Counting 2Count the square-free words of each length from 1 to n over the alphabet {a, b, c}, where n is at most 120.	Hard8	StringBacktracking+1	No attempts yet	2s	512 MB	Judgeable
Necklace ConstructionGiven a target string of up to 300 lowercase letters, find the minimum number of edit and copy-reverse operations to build it from an empty buffer necklace.	Hard8	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Sequence and Queries 40Given a sequence A and modulus M, each query shifts every value by d modulo M and asks for the start index of the k-th smallest suffix in lexicographic order.	Hard8	StringSorting+1	No attempts yet	2s	512 MB	Judgeable
Maze ConstructionBuild a labyrinth of rooms with red, green, and blue corridors where following the repeating color string S from the entrance never reaches the exit.	Hard8	GraphString+1	No attempts yet	3s	1024 MB	Judgeable
XOR Data StructureMaintain a multiset under add, delete-all-min, delete-all-max, and queries for the element minimizing or maximizing v XOR s.	Hard8	TrieBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Edit Distance Yet AgainDecide whether the edit distance between two strings is at most k, and if so, output a minimum-length sequence of insert, delete, and replace operations.	Hard8	StringDynamic programming+1	No attempts yet	20s	512 MB	Judgeable
Baby's First Suffix Array ProblemFor each query substring x = s[l..r], count the suffixes of x that are lexicographically no larger than the suffix s[k..r].	Hard8	StringString matching+1	No attempts yet	14s	512 MB	Judgeable
Fibonacci StringsSum the orders (counts of letter a) of every substring of X that is a Fibonacci string, meaning it has no two adjacent a's, counting each occurrence separately.	Hard8	StringDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Messy kangaroo babiesGiven a word S and a list of candidate synonyms, count how many are subsequences of S that can be embedded in at least two different ways.	Hard8	StringDynamic programming+2	No attempts yet	5s	1024 MB	Judgeable
DecompressionInvert a Burrows-Wheeler style permutation by reconstructing the sorted rotation table from the last-column string, then rotate the result so the period comes first.	Hard8	StringSorting+2	No attempts yet	1s	1024 MB	Judgeable
Dice Password SecurityGiven a dictionary of words with no word a substring of another, count how many n-word concatenations have each queried total length.	Hard8	Dynamic programmingString matching+2	No attempts yet	1s	1024 MB	Judgeable
Almost Prefix-Free CodesChoose the largest subset of given words such that the longest common prefix of any two chosen words has length at most k.	Hard8	TrieTree+2	No attempts yet	2s	1024 MB	Judgeable
Document FormattingSimulate the editor's line and paragraph layout with words and three picture layouts, then output the top-left coordinates of every picture.	Hard8	SimulationImplementation+1	No attempts yet	2s	1024 MB	Judgeable
NamesGiven two strings, find the lexicographically largest string that is a subsequence of both, or print nothing if none exists.	Hard8	StringGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Robot AssemblerGiven a string of N operation types and a memory size K, count the ways to pick a K-character cyclic memory pattern and a starting position so that the robot runs at least K+1 operations before repeating the intended sequence.	Hard8	StringPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Native ExpansesGiven a string and a 0/1 table saying which letter may be deleted right after which letter, delete characters to get the lexicographically smallest result.	Hard8	StringGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Moscow NumbersGiven templates of letters and question marks, replace each ? with a Moscow digit to maximize the number's value, then print that value and the filled string.	Hard8	StringGreedy+1	No attempts yet	1s	1024 MB	Judgeable
«Abracadabra»For each pattern s, count dictionary words t where s is both a prefix and a suffix of t; word and pattern lengths are at most 50.	Hard8	StringHash map+2	No attempts yet	8s	1024 MB	Judgeable
Another Substring Query ProblemGiven a string s and queries each with a pattern t and integer k, find the starting position of the k-th occurrence of t in s, or -1 if it occurs fewer than k times.	Hard8	String matchingString+2	No attempts yet	6s	1024 MB	Judgeable
File ManagerGiven a cyclic list of file names, find the fewest key presses to move the cursor through the requested files using up, down, and Alt-prefix jumps, and print the keys.	Hard8	Shortest pathString+1	No attempts yet	2s	1024 MB	Judgeable
Ancient MachineAnna sees the X, Y, Z layout and sends 0/1 bits so Bruno can remove every device in an order that maximizes good removals, using as few bits as possible.	Hard8	StringGreedy+1	No attempts yet	2s	256 MB	Judgeable
Mutant VaccineGiven up to 100 DNA strings, find the longest substring common to all of them, breaking ties by earliest position in the first string.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Suffixes may Contain PrefixesGiven a target string and a bullet length n, choose a bullet string of length n that maximizes the sum, over all its suffixes, of the longest common prefix length between that suffix and the target.	Hard8	StringDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
String RemovalErase the whole string S using substring deletions that give scores or single-character deletions worth 1 point each, and find the maximum total score.	Hard8	Dynamic programmingString matching+2	No attempts yet	1s	512 MB	Judgeable
Cipher KeyGiven encrypted strings, recover for each the longest string s such that s is a prefix and reversed s is a suffix of some substring t, maximizing t.	Hard8	StringString matching+2	No attempts yet	2s	256 MB	Judgeable
Text EditorMaintain a string of parentheses and letters under point updates, and after each update that sets a parenthesis, report the position of its matching bracket or -1.	Hard8	Segment treeStack+2	No attempts yet	2s	256 MB	Judgeable
LabelCount the cyclic shifts t of the concatenated label that split into dictionary words separated by one or more dots, and list them.	Hard8	String matchingDynamic programming+1	No attempts yet	2s	256 MB	Judgeable
VirusesCount length-n strings over lowercase letters in which every position lies inside some substring that matches one of the m given virus patterns, modulo 1e9+7.	Hard8	Dynamic programmingTrie+2	No attempts yet	2s	256 MB	Judgeable
RepeatsGiven a binary string of length n, find a substring that is some seed repeated as many times as possible, and report the count, seed length, and 1-based start position.	Hard8	StringString matching+2	No attempts yet	6s	512 MB	Judgeable
May I Add a Letter?Given a string that changes by appending a character or deleting the last one, report after each update how many distinct substrings occur at least twice.	Hard8	StringString matching+1	No attempts yet	2.5s	1024 MB	Judgeable
Longest Common Balanced SubstringGiven two bracket strings A and B, find the length of the longest string that is a valid bracket sequence and a substring of both, or 0 if none exists.	Hard8	String matchingPrefix sum+1	No attempts yet	3s	1024 MB	Judgeable
String MagicGiven costs for insert, delete, replace, and rotate-first-to-end, find the cheapest way to turn string X into string Y.	Hard8	Dynamic programmingString+2	No attempts yet	8s	512 MB	Judgeable
Almost Periodic StringFor each query, decide whether the substring S[l..r] can be turned into a string of period t by changing at most one character.	Hard8	StringHash map+2	No attempts yet	2s	512 MB	Judgeable
SubstringA window [l, r] over a string moves by changing one endpoint at a time, and after each of m queries you must count how many distinct substring values have appeared across all windows visited.	Hard8	StringSorting+2	No attempts yet	2s	512 MB	Judgeable
Common PalindromesCount pairs of intervals, one in S and one in T, whose substrings are equal and palindromic; lengths up to 50,000.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Sakura PoetryCount word sequences of total length M following a directed word-connection graph, such that the concatenated string contains exactly one season word exactly once, modulo 1e9+7.	Hard8	Dynamic programmingString matching+2	No attempts yet	8s	512 MB	Judgeable
Adhoc TranslationGiven text words and dictionary words, assign each distinct text word a unique dictionary word, minimizing the total edit distance summed over all occurrences.	Hard8	Dynamic programmingString+2	No attempts yet	8s	512 MB	Judgeable
Princess, a CryptanalystGiven up to 10 short words, find the shortest string that contains every word as a substring, breaking ties by lexicographic order.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	8s	512 MB	Judgeable
Billion Million ThousandGiven dictionary words for powers of ten, parse an unseparated Usoperant numeral as the largest possible number and find the shortest separated expression with the same value.	Hard8	Dynamic programmingString+2	No attempts yet	8s	512 MB	Judgeable
The Devil of GravitySimulate a 2D editor where text segments fall under gravity and merge when adjacent, then report the current segment or ERROR after a command sequence.	Hard8	SimulationImplementation+1	No attempts yet	2s	512 MB	Judgeable
Broken Calculator GameGiven a formula of digits and operators, apply Q range additions mod 12 to its characters and report the evaluated value after each update.	Hard8	Segment treeString+1	No attempts yet	4s	1024 MB	Judgeable
Orange Farm SimulationFor each road in a tree of fields, find the largest XOR of competitiveness values between a field on one side and a field on the other side after cutting that road.	Hard8	TreeTrie+2	No attempts yet	10s	1024 MB	Judgeable
Orange Leaf's Special TrainingGiven an array and Q queries [l, r], sum the longest common prefix length of [l, r] with every subsegment [i, j] of the array, modulo 1e9+7.	Hard8	String matchingSegment tree+1	No attempts yet	8s	1024 MB	Judgeable
Ketek CountingCount the distinct word-palindrome sentences formed by replacing each '?' with a letter and inserting spaces, modulo 998244353.	Hard8	Dynamic programmingString matching	No attempts yet	4s	64 MB	Judgeable
Little LCSCount the ways to fill the question marks in two good ternary strings of length 2n+1 so that their LCS is exactly n.	Hard8	CombinatoricsString+1	No attempts yet	2s	512 MB	Judgeable
Limited CorrespondenceGiven up to 11 pairs of strings, find the shortest non-empty sequence of distinct pair indices whose concatenated left strings equal the concatenated right strings, breaking ties lexicographically.	Hard8	DFSBacktracking+2	No attempts yet	1s	1024 MB	Judgeable
W3W (What 3 Words)Count how many distinct ordered triples of words (repetition allowed) can be joined with dots to form a code whose dot-stripped version equals the queried string S.	Hard8	StringTrie+2	No attempts yet	1s	512 MB	Judgeable
Cell DivisionGiven a mutation rule for each of N cell types and an initial cell, decide whether the observed final string could have been produced by the division process.	Hard8	Dynamic programmingIntervals+2	No attempts yet	3s	512 MB	Judgeable
Beautiful WordsGiven a string A and a set of strings S, find the minimum over all cyclic rotations of A of the longest substring that appears in some string of S.	Hard8	String matchingTrie+2	No attempts yet	1s	1024 MB	Judgeable
Listing PasswordsCount the 0/1 strings of length N that fit the fixed digits and M required palindrome intervals, modulo 1e9+7, or 0 on conflict.	Hard8	Union-findString+1	No attempts yet	3s	1024 MB	Judgeable
Balanced Binary StringCount the ways to replace each '?' in a circular binary string with 0 or 1 so that every two circular substrings of the same length contain numbers of 1s differing by at most one, modulo 1e9+7.	Hard8	StringCombinatorics+2	No attempts yet	3s	512 MB	Judgeable
Longest Lyndon PrefixFor each suffix of a lowercase string, find the length of its longest prefix that is a Lyndon word.	Hard8	StringString matching+1	No attempts yet	1s	256 MB	Judgeable
RatsGiven an infinite periodic string A and a set S of strings, find the minimum number of strings from S whose concatenation forms a string B that tiles the line identically to A.	Hard8	StringGraph+2	No attempts yet	0.75s	256 MB	Judgeable
Gifted ComposerAfter each prepend or append, count the lengths k for which the note sequence is a repetition of period k, with a partial final block allowed.	Hard8	String matchingString	No attempts yet	4s	256 MB	Judgeable
What a Horrible and Dreadful FormulaGiven a string where digits were replaced by English number words, recover the original arithmetic expression or report that none exists, then evaluate it left to right.	Hard8	StringImplementation+2	No attempts yet	1s	256 MB	Judgeable
String ProductGiven a string s, find strings a and b with a times b equal to s (letters add mod 26), minimizing a+b lexicographically, then minimizing \|a\|.	Hard8	StringMath+2	No attempts yet	4s	256 MB	Judgeable
Balanced Rainbow SequenceFlip the fewest brackets so that the sequence stays balanced after removing all lime brackets and after removing all gray brackets.	Hard8	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
Square GraphGiven a sequence and a weight for each half-length k, find the minimum spanning forest weight of the graph built from squares whose two halves match.	Hard8	String matchingUnion-find+2	No attempts yet	5s	256 MB	Judgeable
Filipp RukhovichSum the palindromicity of every subsequence of a string, counting each occurrence of a subsequence, modulo 998244353.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	6s	512 MB	Judgeable
Valid Parenthesis StringA bracket string supports point flips and range queries that count how many ways the characters in [l, r] can be chosen so the whole string becomes a balanced parenthesis sequence.	Hard8	Segment treeCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Scrambled WordsCount dictionary words that appear in a generated string, either as-is or with the middle letters permuted and first and last letters fixed.	Hard8	String matchingHash map+2	No attempts yet	Not set	1024 MB	Judgeable
Funniest Word SearchFind the subgrid of a letter grid that maximizes matched word length divided by width plus height, and count the subgrids that reach that maximum.	Hard8	String matchingTrie+2	No attempts yet	240s	1024 MB	Judgeable
One is zero, zero is onePick strings from set S to concatenate, then reorder the result into binary string t with the fewest adjacent swaps, ties broken lexicographically.	Hard8	Dynamic programmingString+1	No attempts yet	8s	1024 MB	Judgeable
One-Dimensional ChessGiven N sequences, count for each queried value how often it appears as the last common element before two sequences first differ, over all pairs.	Hard8	TriePrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Most EqualGiven N strings over the first M letters, find a K-letter string P (distinct letters, order preserved) that appears as a subsequence in the most strings; report that count, the lexicographically smallest such P, and how many distinct P achieve it.	Hard8	Dynamic programmingString+2	No attempts yet	1s	1024 MB	Judgeable
Number of WordsGiven a run-length compressed string, count the number of distinct subsequences of the fully expanded string, modulo 998244353.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Tomb HaterFind a shortest north-to-south path on a grid that spells a concatenation of given words, moving only south, west, or east without revisiting tiles.	Hard8	Dynamic programmingGraph+2	No attempts yet	4s	1024 MB	Judgeable
SubprimeCount primes among the lth through hth smallest primes whose decimal representation contains the given digit string p, counting each prime once.	Hard8	String matchingMath+2	No attempts yet	2s	1024 MB	Judgeable
Shortest Missing SubsequencesGiven a target string and queries over an alphabet, decide for each query whether it is a shortest string that is not a subsequence of the target.	Hard8	StringGreedy+2	No attempts yet	10s	1024 MB	Judgeable
Rise and FallGiven a huge decimal string, find the largest number no greater than it whose digits split into a nondecreasing prefix and a nonincreasing suffix.	Hard8	GreedyString+2	No attempts yet	1s	1024 MB	Judgeable
Substrings and SubsequencesCharacterize strings whose distinct substrings equal their distinct subsequences, then print the n-th such string in length-then-lexicographic order for n up to 1e6.	Hard8	StringCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
How Many Strings Are LessGiven a set D of strings and a string s, after each suffix overwrite of s, count how many strings in D are lexicographically less than s.	Hard8	TrieSegment tree+1	No attempts yet	2s	512 MB	Judgeable
Reversible CompressionFind the shortest code string whose decoding matches the given digits and still matches when the code is reversed. Ties go to the lexicographically smallest.	Hard8	Dynamic programmingString+1	No attempts yet	2s	1024 MB	Judgeable
Pair ProgrammingCount the distinct expressions formed by interleaving two programs of N instructions each, modulo 10^9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Colorful Bracket SequencesCount the distinct colorful bracket subsequences of a colored bracket string, where adjacent and matched brackets must have different colors.	Hard8	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
Joyful KMPCount the lowercase strings that have the same failure function as the given string, and print the K-th one in lexicographic order or OVER.	Hard8	String matchingCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
RepetitionsGiven a lowercase string of up to 10^6 letters and up to 100 range queries, find the longest square tt inside each range and its leftmost start.	Hard8	String matchingDivide and conquer+1	No attempts yet	10s	512 MB	Judgeable
Decrypting ZodiacGiven an encrypted string and a guessed plaintext, find the minimum letter mismatches over all Caesar shifts and cyclic splits used during encryption.	Hard8	String matchingMath+1	No attempts yet	8s	1024 MB	Judgeable
I Herd You Like Ternary OperatorsCount the distinct parse trees of a parenthesis-free ternary expression made of letters, ? and :, modulo 1,000,000,007.	Hard8	StringStack+1	No attempts yet	1s	1024 MB	Judgeable