Strings and text

Parsing, matching, and tries

Under construction

Still being built. Things may change

Total results3,614 problems

Jumping Frog
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Long Long Strings
Hard8
String, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Flipping Out
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Calendar Fragment
Hard8
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
String Puzzle
Hard8
String, Union-find+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mars
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Retro
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Concert Attendance Schedules
Hard8
Dynamic programming, String
No attempts yet
Time limit
0.3s
Memory limit
128 MB
Judgeable
Vera and the Banquet
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Standing Out from the Herd
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Jet-Black Wings
Hard8
Trie, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Operation Optimization
Hard8
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Big Number Multiplication (2)
Hard8
Math, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hit of the Season
Hard8
String, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Go with the Flow
Hard8
Brute force, String+2
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Magic
Hard8
Hash map, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
XEN 3166
Hard8
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Common Palindromic Substring
Hard8
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Split and Merge
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Opening the Treasure Box
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Lottery
Hard8
String matching, Hash map+2
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Willy Feels Guilty
Hard8
String matching, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hiding Merlin
Hard8
String matching, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Injecting DNA
Hard8
String, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Binary Tree and Sequence
Hard8
String matching, Hash map+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Similar Words
Hard8
Trie, Tree+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Suffix-Freeness
Hard8
String matching, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Isomorphic Inversion
Hard8
Greedy, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Intergalactic Bidding
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Locker Room
Hard8
String, Greedy+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Numbers Generator
Hard8
String matching, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Repeated Substrings
Hard8
String matching, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A/B - 3
Hard8
Math, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Police Hypothesis
Hard8
Tree, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Sequence That Matches Front and Back
Hard8
Array, String matching+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bad Keming
Hard8
String matching, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fraction Challenge
Hard8
String, Hash map+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Distinct Substrings
Hard8
String matching, Math+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
The ABCD Murderer
Hard8
String matching, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shortest Common Non-Subsequence
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Prefix Suffix Search
Hard8
String matching, Trie+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Naming the Computer
Hard8
String matching, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
XOR MST
Hard8
Trie, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequence and Queries 20
Hard8
Trie, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
XOR Submatrix
Hard8
Bit manipulation, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Distinct Substring Queries 2
Hard8
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Substring Replacement
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
K-th Substring
Hard8
String, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Folding
Hard8
String, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting Strings
Hard8
String, Greedy+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
String Decoration
Hard8
String, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Zoo
Hard8
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ali's Typewriter
Hard8
String, Trie+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pipe Marbles
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Third Baseman Unknown
Hard8
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Abbreviation
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Fox Quiz
Hard8
Segment tree, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Dishonest Driver
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
JOI Logo Design
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cell Explosion
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Copy and Paste
Hard8
String, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ICPC
Hard8
Combinatorics, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
K==S
Hard8
String matching, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ambiguous Encoding
Hard8
String matching, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Interleaved Periodic String
Hard8
Brute force, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fantastic Fožgaj
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Strong Jovsi
Hard8
String, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
LCS 6
Hard8
String, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
8 MB
Judgeable
LCS 7
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
8 MB
Judgeable
K-pop Strings
Hard8
String, Dynamic programming+1
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Incomparable Pairs
Hard8
String, Tree+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
The Zong of the Zee
Hard8
String, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Hills And Valleys
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kecleon
Hard8
String, String matching
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Square Substrings
Hard8
String, String matching+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Crazy LCP
Hard8
String, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Exciting Menus
Hard8
Trie, String+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Passwords
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1.5s
Memory limit
64 MB
Judgeable
Banned Words
Hard8
String matching, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Classic Quotation
Hard8
String matching, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Balanced Sequence
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Border
Hard8
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Decomposition
Hard8
String matching, Dynamic programming
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Origami
Hard8
String matching, Hash map+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Mikhail's Problem
Hard8
String, String matching+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Rat-O-Matic
Hard8
Tree, String matching+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Binary Strings
Hard8
Dynamic programming, String matching+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Master Zhu and Palindromes
Hard8
String, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Substring Query
Hard8
String matching, Trie+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Escape Sequences
Hard8
String, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Trener
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
min-xor
Hard8
Trie, Bit manipulation+2
No attempts yet
Time limit
0.4s
Memory limit
8 MB
Judgeable
Related Languages
Hard8
Binary search, Dynamic programming+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Dynamic Input Tool
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Occurrences
Hard8
String matching, Tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Repeating Subsequence Tests
Hard8
String, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Consistent Occurrences
Hard8
String, String matching+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Dissertation
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
A Text Problem
Hard8
String matching, Hash map+1
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Cyclic Shifts
Hard8
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Jumping FrogGiven a circular string of rocks and ponds, count the step sizes K (1 to N-1) for which some rock's K-step cycle stays entirely on rocks.	Hard8	Number theoryMath+2	No attempts yet	1s	1024 MB	Judgeable
Long Long StringsDecide whether two sequences of insertions and deletions, applied to any sufficiently long string, produce identical results.	Hard8	StringMath+2	No attempts yet	1s	512 MB	Judgeable
Flipping OutCount the strings that, added to the given patterns, make the flip rule reproduce the given flip sequence, or -1 if infinitely many work.	Hard8	StringDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Calendar FragmentGiven a small rectangular fragment cut from a fixed-format yearly calendar, list all years from 1900 to 2100 whose calendar could contain that fragment.	Hard8	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
String PuzzleGiven equality hints between substrings of a huge implicit string plus some fixed letters, decide the letters at the queried positions. The hint structure is a partition of the string into sections, and a hint joins one section to an earlier same-length section, so the constraints are interval equalities on an unknown string of length n; the task is to propagate equality and fixed letters across positions, answering ? where a position's letter is not forced. The input size is small (at most 1000 hints and 1000 queries) but n can be 10^9, so positions cannot be enumerated directly and the hint/	Hard8	StringUnion-find+1	No attempts yet	2s	512 MB	Judgeable
MarsFor each query substring, find the minimum number of bit flips that make it match no substring of the DNA, or report Impossible.	Hard8	String matchingDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
RetroGiven a grid where the player moves horizontally while objects fall one row per turn, collect brackets to form the longest valid expression and output the lexicographically smallest one of that length.	Hard8	Dynamic programmingGreedy+2	No attempts yet	0.5s	512 MB	Judgeable
Concert Attendance SchedulesCount the ways to pick increasing day positions matching a target band sequence, where each pick must wait h_b+1 days after that band's previous pick.	Hard8	Dynamic programmingString	No attempts yet	0.3s	128 MB	Judgeable
Vera and the BanquetGiven a circular string S, count the number of distinct substrings appearing in any contiguous block read in either direction around the circle.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Standing Out from the HerdFor each name in the herd, count its substrings that occur in no other name.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
The Jet-Black WingsMaintain a multiset under global XOR updates and queries asking for the sum of the K smallest elements.	Hard8	TrieBit manipulation+2	No attempts yet	3s	512 MB	Judgeable
Operation OptimizationFind the shortest sequence of append-0, append-1, and self-doubling operations whose two-fold application to the empty string yields a given binary string S.	Hard8	StringGreedy+2	No attempts yet	2s	256 MB	Judgeable
Big Number Multiplication (2)Multiply two integers of up to 300,000 digits each, too large for quadratic multiplication, and print the exact product.	Hard8	MathDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Hit of the SeasonFind the shortest print matrix over R, G, B that can reproduce a wallpaper string, where specified stripes must never be overprinted and at most 19 stripes are unspecified.	Hard8	StringBrute force+2	No attempts yet	2s	512 MB	Judgeable
Go with the FlowChoose a line width for justified monospaced text, then find the longest run of spaces that drifts by at most one column per line, and report the best width and length.	Hard8	Brute forceString+2	No attempts yet	12s	1024 MB	Judgeable
MagicCount substrings of an N-character string in which all K distinct letters of the whole string appear an equal number of times, modulo 1e9+7.	Hard8	Hash mapPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
XEN 3166Assign each country a length-K subsequence starting with its first letter so that code order matches name lexicographic order, or report impossible.	Hard8	GreedyString+1	No attempts yet	2s	512 MB	Judgeable
Longest Common Palindromic SubstringGiven up to 50 strings with total length 1,000,000, find the length of the longest palindrome that occurs as a substring in every one of them.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Split and MergeGiven two tilings of a 1xL board by 1x1 and 1x2 pieces, find the minimum number of split/merge operations to transform one into the other and count the ways.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Opening the Treasure BoxFor each start position, find the minimum replacement cost plus walking cost (c per step) to make the letter string a palindrome.	Hard8	Dynamic programmingString+1	No attempts yet	1s	256 MB	Judgeable
LotteryFor each of n-l+1 length-l windows and each query threshold k, count how many other windows differ from it in at most k positions.	Hard8	String matchingHash map+2	No attempts yet	2s	32 MB	Judgeable
Willy Feels GuiltyBuy, throw, or swap products so the delivered sequence realizes a fixed menu at minimum total cost.	Hard8	String matchingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Hiding MerlinDecompose a digit string into concatenated perfect squares, each at most 10 digits and starting with 1 to 9, and report the smallest possible total sum.	Hard8	String matchingDynamic programming+2	No attempts yet	4s	512 MB	Judgeable
Injecting DNAFor every suffix of a string, compute its toxicity from the number of out-of-order suffix pairs, then output the length of the suffix with the largest effectiveness.	Hard8	StringSorting+2	No attempts yet	2s	512 MB	Judgeable
Binary Tree and SequenceFind the smallest tree depth where one concatenated leaf sequence occurs at least K times under a periodic leaf pattern.	Hard8	String matchingHash map+2	No attempts yet	3s	256 MB	Judgeable
Similar WordsGiven a set of distinct words, choose as many prefixes as possible so that no two chosen words differ by deleting one leading letter.	Hard8	TrieTree+2	No attempts yet	4s	512 MB	Judgeable
Suffix-FreenessGiven a DFA with n at most 2000 states and f final states, decide whether some accepted string is a proper suffix of another accepted string, and answer 1 or 0.	Hard8	String matchingGraph+2	No attempts yet	2s	512 MB	Judgeable
Isomorphic InversionSplit a digit string into the largest number of contiguous pieces whose sequence of pieces reads the same forward and backward.	Hard8	GreedyString matching+2	No attempts yet	1s	512 MB	Judgeable
Intergalactic BiddingGiven up to 1000 bidders with huge distinct bids and a huge target s, find every bidder contained in a subset whose sum is exactly s.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Locker RoomPick length-K substrings from a cyclic string covering every position and minimize their lexicographic maximum.	Hard8	StringGreedy+2	No attempts yet	6s	512 MB	Judgeable
Numbers GeneratorGiven up to ten H/T patterns of the same length, compute the expected number of fair coin flips until one pattern first appears contiguous.	Hard8	String matchingHash map+2	No attempts yet	2s	512 MB	Judgeable
Repeated SubstringsFind the longest substring with at least two overlapping occurrences in a string of up to 10^5 letters, breaking ties by the smallest in lexicographic order.	Hard8	String matchingString+2	No attempts yet	2s	512 MB	Judgeable
A/B - 3Given A and B with up to 10000 digits (possibly negative), compute the quotient and nonnegative remainder of A divided by B.	Hard8	MathImplementation+2	No attempts yet	0.5s	512 MB	Judgeable
Police HypothesisGiven a tree with one letter per vertex, count how often pattern P appears on the path between two vertices, and handle letter updates.	Hard8	TreeString matching+2	No attempts yet	2s	512 MB	Judgeable
A Sequence That Matches Front and BackChoose how many elements to cut from the array's front so that, if the rest is a k-front-back sequence, k is as large as possible or no k exists. Return k and the cut count.	Hard8	ArrayString matching+1	No attempts yet	2s	128 MB	Judgeable
Bad KemingFill every gap in the spaced copy of S with chosen letters to make the longest prefix of S a contiguous substring, and find that prefix length.	Hard8	String matchingString+2	No attempts yet	2s	512 MB	Judgeable
Fraction ChallengeMultiply many huge fractions given as digit strings and output the reduced product as a/b.	Hard8	StringHash map+2	No attempts yet	0.5s	512 MB	Judgeable
Distinct SubstringsGiven a period string p and length n, count distinct substrings of the string formed by repeating p and cutting to n. n may be 1e9.	Hard8	String matchingMath+1	No attempts yet	3s	512 MB	Judgeable
The ABCD MurdererFind the fewest word occurrences needed to cover a target text exactly when cut-outs may overlap on matching text, or report -1 if impossible.	Hard8	String matchingArray+2	No attempts yet	2s	512 MB	Judgeable
Shortest Common Non-SubsequenceGiven two binary strings of length up to 4000, find the shortest binary string that is a subsequence of neither, breaking ties by lexicographic order.	Hard8	Dynamic programmingGreedy+2	No attempts yet	5s	512 MB	Judgeable
Prefix Suffix SearchGiven N words and Q prefix/suffix pairs, report for each query how many words match both prefix and suffix. Total input length is up to 2.5 million.	Hard8	String matchingTrie+2	No attempts yet	3s	512 MB	Judgeable
Naming the ComputerGiven a string S and integer K, find the shortest string that contains S as a substring at least K times, and output its length.	Hard8	String matchingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
XOR MSTGiven N labeled vertices where the edge between any two has weight equal to the XOR of their labels, find the total cost of the minimum spanning tree.	Hard8	TrieMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Sequence and Queries 20Maintain a multiset that starts with only 0, supporting insert, delete, and max-XOR queries where every element is XORed with x.	Hard8	TrieBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
XOR SubmatrixBuild the N by M matrix with A[i][j] = V[i] xor U[j] and find the submatrix whose elementwise xor is maximal.	Hard8	Bit manipulationTrie+2	No attempts yet	2s	512 MB	Judgeable
Distinct Substring Queries 2Process a stream of append-character and count-distinct-substrings queries on a growing string, answering each count query online.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Substring ReplacementReplace each question mark in S with a lowercase letter so that T appears as a substring as many times as possible, and report that maximum count.	Hard8	Dynamic programmingString matching+2	No attempts yet	2s	512 MB	Judgeable
K-th SubstringGiven a string S, answer queries that ask for the K-th distinct substring of S in lexicographic order, or -1 if it does not exist.	Hard8	StringTrie+2	No attempts yet	2s	512 MB	Judgeable
String FoldingFold the string at a sequence of positions into vertical columns, then find the longest column-run of one repeated character that starts at the bottom with no gaps.	Hard8	StringBrute force+2	No attempts yet	2s	512 MB	Judgeable
Cutting StringsGiven a string s and an integer k, remove at most k non-overlapping substrings to get the lexicographically largest remaining string.	Hard8	StringGreedy+1	No attempts yet	10s	512 MB	Judgeable
String DecorationGiven a string S and N pattern strings, find the length of the shortest substring of S that contains every pattern as a substring.	Hard8	StringSliding window+2	No attempts yet	2s	512 MB	Judgeable
ZooGiven a string, count for each prefix the non-overlapping prefix-suffix matches and output the product of (count+1) modulo 1e9+7.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Ali's TypewriterGiven a keypress sequence that builds strings in a buffer and prints them, answer queries counting how often printed string x occurs inside printed string y.	Hard8	StringTrie+2	No attempts yet	1s	512 MB	Judgeable
Pipe MarblesGiven two binary strings as stacks, count the sum of squares of the number of interleavings producing each distinct output string, modulo 1024523.	Hard8	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Third Baseman UnknownOn an N by N grid of uppercase letters, walk right or down from the top-left to the bottom-right and maximize how many times "MOLA" appears in the collected string.	Hard8	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
AbbreviationCount the ways to split a query string into pieces, where each piece is a prefix of some dictionary word, with duplicates counted as distinct.	Hard8	Dynamic programmingString matching+2	No attempts yet	2.5s	1024 MB	Judgeable
Fox QuizGiven answer strings S and T over O/X, answer range queries and point flips: for a range, choose positions to mark F to maximize A times correct answers plus B times occurrences of the consecutive pattern F,O,X.	Hard8	Segment treeDynamic programming+2	No attempts yet	3s	1024 MB	Judgeable
Dishonest DriverGiven a string of N characters, find the size of the shortest compressed form built from single characters, concatenation, and repetition (C repeated k times).	Hard8	Dynamic programmingString+2	No attempts yet	6s	512 MB	Judgeable
JOI Logo DesignGiven a circular string of length 4^K over {J,O,I}, find the rotation that minimizes mismatches with a level-K JOI sequence built by recursive quarter block replacement.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Cell ExplosionGiven cell division rules and a target sequence S, find the first minute when S appears as a contiguous segment of the worm's cell sequence, or report -1.	Hard8	String matchingDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Copy and PasteGiven a string of up to 200,000 lowercase letters, find the length of the longest substring that appears at least twice at disjoint positions, or -1 if none exists.	Hard8	StringBinary search+2	No attempts yet	2s	512 MB	Judgeable
ICPCConcatenate all lowercase words of length 1 through N in length-then-alphabetical order; count occurrences of the substring "icpc" modulo 1e9+7, with N up to 1e9.	Hard8	CombinatoricsString matching+2	No attempts yet	2s	512 MB	Judgeable
K==SCount sequences of length N over 26 letters that avoid any of Q given forbidden strings as contiguous substrings, modulo 1e9+7, where N can be up to 1e9.	Hard8	String matchingDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Ambiguous EncodingGiven a set of distinct binary codewords, decide whether two different character sequences can encode to the same bit string, and if so print the length of the shortest such string.	Hard8	String matchingBFS+2	No attempts yet	2s	512 MB	Judgeable
Interleaved Periodic StringGiven a binary string S, find the minimum total length of two binary strings whose repeated copies can be interleaved to produce S.	Hard8	Brute forceDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Fantastic FožgajCount length-m lowercase strings over 26 letters that avoid any of n forbidden patterns as a substring, modulo 1e9+7, with m up to 1e9.	Hard8	Dynamic programmingString matching+2	No attempts yet	1.5s	512 MB	Judgeable
Strong JovsiCount the sequences of palindromic substrings (l1,r1) to (lk,rk) where l strictly increases and r strictly decreases, modulo 998244353.	Hard8	StringDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
LCS 6Given two uppercase strings of up to 50000 characters, print the length of their longest common subsequence.	Hard8	StringDynamic programming+1	No attempts yet	1s	8 MB	Judgeable
LCS 7Given two strings of length up to 50000, find the length of their longest common subsequence and print one such subsequence.	Hard8	StringDynamic programming+2	No attempts yet	2s	8 MB	Judgeable
K-pop StringsCount strings of length n over 35 characters that contain no tandem repeat of length n-k or more, modulo 998244353.	Hard8	StringDynamic programming+1	No attempts yet	7s	512 MB	Judgeable
Incomparable PairsCount unordered pairs of substrings of a string s where neither substring is contained in the other.	Hard8	StringTree+1	No attempts yet	3s	512 MB	Judgeable
The Zong of the ZeeGiven m lines of length n with at most one unknown letter per line, count the permutations that turn each line into the next one, modulo 1e9+7.	Hard8	StringCombinatorics+1	No attempts yet	3s	512 MB	Judgeable
Hills And ValleysGiven a sequence of digits, find the interval to reverse so that the longest non-decreasing subsequence is as long as possible, and report that length with the interval.	Hard8	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
KecleonColors join a line one at a time, and each query counts how many length-k windows equal the first k colors of the line.	Hard8	StringString matching	No attempts yet	4s	512 MB	Judgeable
Square SubstringsGiven a lowercase string and range queries, count the square substrings (even-length strings tt) fully inside each query range.	Hard8	StringString matching+2	No attempts yet	8s	512 MB	Judgeable
Crazy LCPGiven N strings and Q range queries, for each range [L, R] report the maximum longest common prefix over all pairs of distinct strings in that range.	Hard8	StringTrie+2	No attempts yet	2s	512 MB	Judgeable
Exciting MenusGiven N strings with a joy value per position, maximize over all substrings the product of its length, the joy at its end, and the number of strings having it as a prefix.	Hard8	TrieString+2	No attempts yet	4s	512 MB	Judgeable
PasswordsGiven n rows of m letters, permute the columns so the rows become lexicographically nondecreasing, choosing the smallest such permutation or reporting NIE.	Hard8	GreedySorting+2	No attempts yet	1.5s	64 MB	Judgeable
Banned WordsCount length-L strings over 26 letters avoiding a given set of banned substrings, modulo 998244353, with L up to 1e9.	Hard8	String matchingTrie+2	No attempts yet	2s	512 MB	Judgeable
Classic QuotationGiven strings S and T and queries (L, R), compute the expected number of occurrences of T after deleting a random substring spanning positions L to R, scaled by the number of choices.	Hard8	String matchingPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Balanced SequenceReorder n bracket strings to maximize the length of the longest balanced subsequence of their concatenation.	Hard8	GreedySorting+2	No attempts yet	1s	256 MB	Judgeable
BorderGiven a string generated from a seed, compute the sum over all pairs i<j of the longest k where the prefix starting at i of length k equals the suffix ending at j of length k.	Hard8	StringString matching+1	No attempts yet	2s	512 MB	Judgeable
DecompositionFor each string, sum the products of smallest periods over all ways to split it into substrings, modulo 1e9+7.	Hard8	String matchingDynamic programming	No attempts yet	3s	512 MB	Judgeable
OrigamiCount the distinct submatrices of a letter grid that folding can produce, where each fold needs every mirrored pair of cells on the folded part to match in color.	Hard8	String matchingHash map+1	No attempts yet	1s	256 MB	Judgeable
Mikhail's ProblemGiven a string and several index ranges [l, r], count the distinct palindromic substrings inside each range s[l..r].	Hard8	StringString matching+1	No attempts yet	3s	512 MB	Judgeable
Rat-O-MaticFrames nest into a tree, and each query asks how many database melodies contain the sound string of the path from outside to an active frame.	Hard8	TreeString matching+1	No attempts yet	3s	256 MB	Judgeable
Binary StringsCount the antisymmetric binary strings of length 2L that contain each of n given binary strings (n up to 6, length up to 20) as a substring, modulo 998244353.	Hard8	Dynamic programmingString matching+1	No attempts yet	1s	512 MB	Judgeable
Master Zhu and PalindromesFor each query, count the distinct palindromic substrings of S[L..R] whose tail starts with the given string T.	Hard8	StringTrie+2	No attempts yet	2s	512 MB	Judgeable
Substring QueryGiven n strings of a and b, answer q queries: how many strings with index in [l, r] contain the pattern P as a substring.	Hard8	String matchingTrie+1	No attempts yet	10s	512 MB	Judgeable
Escape SequencesFor a morphism f that replaces a with aa and b with ab, find the smallest k such that t is a substring of the k-fold iterate f^k(s).	Hard8	StringDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
TrenerCount ways to pick one surname from each length bucket so every shorter surname is a substring of every longer one, modulo 1e9+7.	Hard8	StringDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
min-xorMaintain a dynamic set under insertions and deletions, and after each min-xor query report the smallest XOR of any two elements currently in the set.	Hard8	TrieBit manipulation+2	No attempts yet	0.4s	8 MB	Judgeable
Related LanguagesGiven strings A and B and an integer k, find the longest pair of equal-length substrings, one from each string, that differ in at most k positions.	Hard8	Binary searchDynamic programming+2	No attempts yet	10s	512 MB	Judgeable
Dynamic Input ToolFind the minimum number of append-character and append-subsequence-of-current-string operations needed to build a given string from empty.	Hard8	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
New OccurrencesFor each prefix of a string S, print the sum of squared occurrence counts over all distinct substrings of that prefix.	Hard8	String matchingTree+1	No attempts yet	1s	1024 MB	Judgeable
Repeating Subsequence TestsGiven a string and up to 10^6 generated substring queries, count distinct subsequences of each substring modulo 10^9+7 and output the last answer.	Hard8	StringPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Consistent OccurrencesGiven a string s and many query strings, for each query find the largest set of non-overlapping occurrences of that query string in s.	Hard8	StringString matching+2	No attempts yet	4s	512 MB	Judgeable
DissertationFor each test case, compute the length of the longest common subsequence of a long book string and a short dissertation string.	Hard8	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
A Text ProblemFor each query string, count the positions in T where it occurs with at most one mismatched letter.	Hard8	String matchingHash map+1	No attempts yet	6s	512 MB	Judgeable
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