Strings and text

Parsing, matching, and tries

Under construction

Still being built. Things may change

Total results3,615 problems

Common Substring Queries
Hard8
String matching, Tree+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
VEZUV
Hard8
Trie, Graph+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Yeoksam Station
Hard8
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Suffix Sort
Hard8
String, String matching+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Lexicographic Comparison
Hard8
Array, String matching+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
String Strange Sum
Hard8
String matching, String+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
LCS 9
Hard8
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Foreign Football
Hard8
String matching, String+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Keyboard Queries
Hard8
Union-find, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Longest Substring
Hard8
String matching, Tree
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Folding
Hard8
String matching, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Qarentheziz Sequence
Hard8
Segment tree, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Palindrome
Hard8
String matching, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bajtessi's Dribbling
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable
Chino's Latte Art
Hard8
Geometry, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Listening Test Practice
Hard8
String matching, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Qizz Quzz (Hard)
Hard8
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Copier
Hard8
String matching, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Robot Programming Strategy
Hard8
String, Greedy+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Piling Papers
Hard8
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pareidolia
Hard8
Segment tree, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Binary Sequence and Queries
Hard8
Segment tree, String+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
LCSLCSLCS
Hard8
Dynamic programming, String
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Encrypted Message
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Suspicious Reports
Hard8
String matching, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cipher Key
Hard8
String, String matching
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Race
Hard8
Trie, String+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mavis at School
Hard8
Divide and conquer, Stack+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
A String Puzzle
Hard8
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Spells
Hard8
Dynamic programming, String matching+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Jedi Queries
Hard8
Trie, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Richelieu's Parades
Hard8
String matching, Trie+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Lazybugs and the Fence
Hard8
String matching, Number theory+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Carpet
Hard8
String matching, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Scar Prepares an Attack
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Rafiki's Test
Hard8
String, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Supersubstring
Hard8
String matching, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Blind Flibs
Hard8
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Regular Expression Edit Distance
Hard8
Dynamic programming, Recursion+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
BX Bet
Hard8
Game theory, Trie+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Aperiodic Appointments
Hard8
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rigged Lottery
Hard8
String, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Little Substring Problem
Hard8
String matching, Trie+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Abstracts
Hard8
String, String matching
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
K-Lottery
Hard8
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Labelled Paths
Hard8
Dynamic programming, Topological sort+2
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Suffix Automaton
Hard8
String, String matching+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Many LCS
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Macaron Kama
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Missing Number
Hard8
String, Implementation+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Tip of Your Tongue
Hard8
String, Trie+1
No attempts yet
Time limit
4s
Memory limit
2048 MB
Judgeable
Inverse KMP
Hard8
String matching, Combinatorics
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
ABC String
Hard8
String, Greedy+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Pirate Code
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The 'Winning' Gene
Hard8
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Compression
Hard8
String matching, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Champernowne Substring
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
10s
Memory limit
2048 MB
Judgeable
Substring Sort
Hard8
String, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Natural Number Streamer
Hard8
String, String matching+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Password Protection
Hard8
String matching, Combinatorics+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Lexicopolis
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Double Deck
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Champernowne Subsequence
Hard8
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
String Rank
Hard8
String, Greedy+1
No attempts yet
Time limit
0.5s
Memory limit
2048 MB
Judgeable
Interstellar Intervals
Hard8
Dynamic programming, String matching
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Sorting Machine
Hard8
String, Sorting+2
No attempts yet
Time limit
1.5s
Memory limit
2048 MB
Judgeable
Interesting Words
Hard8
Dynamic programming, String matching+1
No attempts yet
Time limit
3s
Memory limit
2048 MB
Judgeable
Palindrome Strings
Hard8
String matching, String
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Sending Substrings
Hard8
String matching, String+1
No attempts yet
Time limit
6s
Memory limit
2048 MB
Judgeable
Shom Language
Hard9
Graph, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
All Closed-Walk Lengths
Hard9
Graph, Matrix+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Shom Code
Hard9
Trie, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hangul-Missing Numbers
Hard9
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hard Matching
Hard9
String matching, Prefix sum+2
No attempts yet
Time limit
30s
Memory limit
1536 MB
Judgeable
Casting Spells
Hard9
String matching, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
K’ak’-u-pakal and the Maya Script
Hard9
Recursion, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Outsourcing
Hard9
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Most Powerful Spell
Hard9
Graph, Shortest path+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Old Memories
Hard9
String matching, Dynamic programming+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Contact
Hard9
String, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Version-Controlled IDE
Hard9
Tree, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Synnerg Lifeform
Hard9
Dynamic programming, Intervals+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jukebox
Hard9
String, Brute force+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Exam
Hard9
Dynamic programming, String matching+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Purify
Hard9
String, Trie+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Accountant Notes
Hard9
String matching, Hash map+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Suffix Array Reconstruction
Hard9
String, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Axes of Symmetry
Hard9
String matching, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Isles in a Triangular Grid
Hard9
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Code
Hard9
Trie, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hamsters
Hard9
String matching, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Periodicity
Hard9
String, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Computational Biology
Hard9
String, Sorting+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Fragments
Hard9
String matching, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quasi-template
Hard9
String matching, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fibonacci Word
Hard9
String, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prefix-Suffixes
Hard9
String matching, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimum brackets
Hard9
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Palindromic Equivalence
Hard9
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Puzzle
Hard9
String matching, Trie+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Common Substring QueriesGiven N strings with total length up to 200,000, answer Q queries, each asking how many distinct substrings strings S_i and S_j share.	Hard8	String matchingTree+1	No attempts yet	4s	1024 MB	Judgeable
VEZUVFor each team name, find an alphabet permutation that makes it lexicographically smallest among all names, or output nemoguce if none exists.	Hard8	TrieGraph+2	No attempts yet	1.5s	1024 MB	Judgeable
Yeoksam StationCount the distinct substrings of S that contain a palindrome of length at least K.	Hard8	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Suffix SortSort all suffixes of a lowercase string by their minimal representation, where each new letter is renamed to the next unused letter in order, and print the start indices.	Hard8	StringString matching+1	No attempts yet	4s	1024 MB	Judgeable
Lexicographic ComparisonGiven permutations a and p under position swaps, compare A_x and A_y lexicographically, where A_k is a with p applied k-1 times.	Hard8	ArrayString matching+2	No attempts yet	2s	1024 MB	Judgeable
String Strange SumGiven a lowercase string s, sum over all segments [l, r] with 2 <= l <= r <= \|s\| the longest suffix of s[1, l-1] that splits into prefixes of s[l, r].	Hard8	String matchingString+1	No attempts yet	4s	1024 MB	Judgeable
LCS 9Given strings A and B, sum the LCS lengths over every prefix of A paired with every substring of B.	Hard8	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
Foreign FootballGiven the concatenation of every ordered pair of n team names, recover the names and report whether the answer is none, unique, or many.	Hard8	String matchingString+1	No attempts yet	5s	1024 MB	Judgeable
Keyboard QueriesGiven palindrome facts about substrings of S, decide whether two substrings must be equal, cannot be equal, or remain undetermined.	Hard8	Union-findString matching+1	No attempts yet	1s	1024 MB	Judgeable
Longest SubstringFor each k from 1 to n, find the longest substring that occurs exactly k times and allows the most non-overlapping occurrences, then print the lengths.	Hard8	String matchingTree	No attempts yet	5s	1024 MB	Judgeable
FoldingGiven a string, count the foldings whose fold positions form an arithmetic set and where every pile holds only one letter.	Hard8	String matchingMath+1	No attempts yet	2s	1024 MB	Judgeable
Qarentheziz SequenceGiven a parentheses string with range flips, find for each query the fewest end insertions and adjacent swaps needed to make a substring balanced.	Hard8	Segment treeString+1	No attempts yet	2s	1024 MB	Judgeable
PalindromeGiven N numbers with fixed digit lengths, find the fewest elements to replace so their concatenation becomes a palindrome.	Hard8	String matchingTwo pointers+1	No attempts yet	1s	1024 MB	Judgeable
Bajtessi's DribblingFor each pair of dribbles, count the distinct balanced, left-sided subsequences of their concatenation, modulo 1e9+7.	Hard8	Dynamic programmingString+1	No attempts yet	9s	1024 MB	Judgeable
Chino's Latte ArtGiven a simple polygon, decide whether one reflex vertex and one convex vertex form a symmetry axis that splits it into two convex halves.	Hard8	GeometryString matching+1	No attempts yet	1s	1024 MB	Judgeable
Listening Test PracticeFor each query, count the substrings of S whose longest common prefix with T[i..j] is exactly k characters.	Hard8	String matchingSorting+1	No attempts yet	3s	1024 MB	Judgeable
Qizz Quzz (Hard)Given a sequence of labels, find the longest prefix that some set of divisor-to-string rules in a Generalized Fizz Buzz program could produce.	Hard8	StringString matching+1	No attempts yet	1s	1024 MB	Judgeable
CopierGiven a sequence built by repeatedly copying a contiguous block and inserting the copy to its right, recover the original permutation of 1 to l.	Hard8	String matchingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Robot Programming StrategyFind a move string that wins a single-elimination bracket against all given opponent programs, whatever the seating order, or report IMPOSSIBLE.	Hard8	StringGreedy+2	No attempts yet	20s	1024 MB	Judgeable
Piling PapersFor each query range of digits, count the ways to add each digit to the top, the bottom, or skip it so the final number lies in [A, B], modulo 1e9+7.	Hard8	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
PareidoliaSum B(s) over all substrings of t, where B(s) is the most copies of "bessie" that can be picked as subsequences of s, after each single-character update.	Hard8	Segment treeDynamic programming+1	No attempts yet	4s	1024 MB	Judgeable
Binary Sequence and QueriesGiven a binary array with point updates, each range query asks for a subsegment whose longest run of 0s is x and longest run of 1s is y, or -1 if none exists.	Hard8	Segment treeString+1	No attempts yet	3s	1024 MB	Judgeable
LCSLCSLCSGiven strings A and B and repeat counts n and m (up to 10^15), find the LCS length of A repeated n times and B repeated m times.	Hard8	Dynamic programmingString	No attempts yet	10s	1024 MB	Judgeable
Encrypted MessageSplit the string t into words so that t is w1 to wn followed by wn to w1, with the maximum possible number of words, then print them.	Hard8	String matchingDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Suspicious ReportsGiven a full histogram s and a sequence t, decide whether some cut height h makes t equal the heights above h, and if so, output the matching column indices.	Hard8	String matchingArray+1	No attempts yet	1s	1024 MB	Judgeable
Cipher KeyGiven a lowercase string s of length up to 500000, find the maximum of \|t\| + f(t)^2 over all substrings t, where f(t) is the longest proper border of t.	Hard8	StringString matching	No attempts yet	2s	1024 MB	Judgeable
RacePick a subset of license plates that maximizes the count times the longest common prefix length times the longest common suffix length.	Hard8	TrieString+2	No attempts yet	2s	1024 MB	Judgeable
Mavis at SchoolGiven an array, find the segment whose maximum times its XOR sum is largest, and print that product.	Hard8	Divide and conquerStack+2	No attempts yet	3s	1024 MB	Judgeable
A String PuzzleFor each substring, count the pointer moves needed to take every character so the answer comes out sorted, with the pointer wrapping around the string.	Hard8	StringGreedy+2	No attempts yet	2s	1024 MB	Judgeable
SpellsFind the fewest concatenation and multiplication steps, using the given spells, that build string t, or report -1 if impossible.	Hard8	Dynamic programmingString matching+1	No attempts yet	3s	1024 MB	Judgeable
Jedi QueriesGiven n numbers and queries with ? wildcards, sum over every filled-in subquery how many numbers are at least that subquery.	Hard8	TrieDynamic programming+1	No attempts yet	3s	1024 MB	Judgeable
Richelieu's ParadesFor each j, delete one length-j substring from t and find the most rows s_i whose prefix is the remaining string. Print the maximum for every j.	Hard8	String matchingTrie+1	No attempts yet	2s	1024 MB	Judgeable
Lazybugs and the FenceFor each lazybug count i, find the fewest shift commands that paint exactly the '#' boards of the fence, or report -1 if impossible.	Hard8	String matchingNumber theory+1	No attempts yet	2s	1024 MB	Judgeable
CarpetCount substrings s[i..j] that split into a piece occurring entirely left of i and a piece occurring entirely right of j, joined in order.	Hard8	String matchingDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
Scar Prepares an AttackCount the ways to pick a nonempty subsequence of each hyena's genotype so that each chosen birth genotype is stronger than the next, modulo 1e9+7.	Hard8	Dynamic programmingString+2	No attempts yet	2s	1024 MB	Judgeable
Rafiki's TestFind the base x and modulus p of a polynomial string hash by querying the hash of chosen strings in an interactive session.	Hard8	StringMath+2	No attempts yet	2s	1024 MB	Judgeable
SupersubstringGiven a text t and many queries s, split each s into the fewest pieces that are substrings of t and print them joined by \|, or NO if impossible.	Hard8	String matchingGreedy	No attempts yet	2s	1024 MB	Judgeable
Blind FlibsGiven a binary word w, find for each k from 1 to \|w\| the maximum predictive power of a k-state blind automaton that predicts the endlessly repeated string w*.	Hard8	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Regular Expression Edit DistanceGiven two regular expressions over a and b, find the minimum edit distance between any string matched by the first and any string matched by the second.	Hard8	Dynamic programmingRecursion+1	No attempts yet	5s	1024 MB	Judgeable
BX BetTwo players alternately add a chosen earlier opponent number to their own, digit-wise mod 10, and the task is to find the winner from both notebooks.	Hard8	Game theoryTrie+1	No attempts yet	2s	1024 MB	Judgeable
Aperiodic AppointmentsCount the ones in a binary string of length N, where each new bit is 1 exactly when the string ends in a K-th power of some nonempty block.	Hard8	StringString matching+1	No attempts yet	1s	1024 MB	Judgeable
Rigged LotteryGiven k, c, and a ticket of length k, find the shortest sequence over 1 to c that contains every length-k sequence as a subsequence except that ticket.	Hard8	StringCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
A Little Substring ProblemGiven a text t and a set of distinct patterns, answer queries by counting how many pattern occurrences lie fully inside t[l..r].	Hard8	String matchingTrie+1	No attempts yet	4s	1024 MB	Judgeable
AbstractsFor each article, find the shortest substring that appears in no other article, breaking ties by lexicographic order, or report that none exists.	Hard8	StringString matching	No attempts yet	3s	1024 MB	Judgeable
K-LotteryGiven M permutation tickets of length K, find the earliest window of K consecutive numbers in the sequence whose relative order matches a sold ticket.	Hard8	String matchingString+1	No attempts yet	2s	2048 MB	Judgeable
Labelled PathsGiven a DAG whose edge labels are substrings of one string A, find the lexicographically smallest path label from s to every vertex.	Hard8	Dynamic programmingTopological sort+2	No attempts yet	15s	1024 MB	Judgeable
Suffix AutomatonGiven a string S, find the k-th distinct substring when all substrings are sorted by length, then lexicographically, and print its first occurrence positions.	Hard8	StringString matching+1	No attempts yet	6s	1024 MB	Judgeable
Many LCSGiven K, construct two binary strings of length at most 8848 that have exactly K distinct longest common subsequences.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	4s	1024 MB	Judgeable
Macaron KamaPair each red shell with a blue shell from the same multiset so each macaron takes the larger size, and maximize the resulting digit string if it is a palindrome.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Missing NumberGiven the digits of consecutive integers from a to b joined together with one integer removed, list every value that could have been the eaten number.	Hard8	StringImplementation+1	No attempts yet	2s	2048 MB	Judgeable
Tip of Your TongueGiven dictionary words, answer queries that count words with prefix p and suffix s (equal length) combined by AND, OR, or XOR.	Hard8	StringTrie+1	No attempts yet	4s	2048 MB	Judgeable
Inverse KMPGiven a string's KMP prefix-function array and the alphabet size c, count the strings that produce that array, modulo 1e9+7.	Hard8	String matchingCombinatorics	No attempts yet	1s	1024 MB	Judgeable
ABC StringPartition a string with equal counts of A, B, and C into the fewest subsequences, where each subsequence splits into consecutive triples that each contain one of every letter.	Hard8	StringGreedy+1	No attempts yet	1s	2048 MB	Judgeable
Pirate CodeFor each length k up to n, sum the decoded values of all binary codes of length k under Fibonacci pirate splitting, modulo 10^9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
The 'Winning' GeneFor each (K, L) pair, collect the start positions of the lexicographically smallest length-L substring in every length-K window, then count pairs by set size.	Hard8	StringString matching+1	No attempts yet	1s	1024 MB	Judgeable
CompressionGiven a binary string, repeatedly remove one copy of any consecutive repeated substring and output the shortest string that can be reached.	Hard8	String matchingString+1	No attempts yet	1s	1024 MB	Judgeable
Champernowne SubstringFill each ? in the pattern with a digit to minimize the index where it first appears in the Champernowne string, printed mod 998244353.	Hard8	Dynamic programmingString+2	No attempts yet	10s	2048 MB	Judgeable
Substring SortEach query sorts the three substrings A[l..r], B[l..r], and C[l..r] and writes them back in sorted order. Print the final A, B, and C.	Hard8	StringSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Natural Number StreamerGiven a binary string, find the longest substring that is the concatenation of consecutive binary numbers starting from some l.	Hard8	StringString matching+1	No attempts yet	3s	1024 MB	Judgeable
Password ProtectionCount length-n lowercase strings that contain the first name or the last name as a contiguous substring, modulo 1,000,000,007.	Hard8	String matchingCombinatorics+1	No attempts yet	8s	1024 MB	Judgeable
LexicopolisFind the lexicographically smallest walk of exactly k edges from s to t, comparing edge magic numbers, and output its polynomial value modulo 1e9+7.	Hard8	GraphDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Double DeckFind the maximum number of matched pairs between two decks of N*K cards, where each mismatch discards the top card of one deck.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
Champernowne SubsequenceGiven a digit string, find the smallest k such that the string is a subsequence of the Champernowne word formed by concatenating 1 through k.	Hard8	StringGreedy+2	No attempts yet	2s	2048 MB	Judgeable
String RankGiven a string w of length up to 3 times 10^6, find the smallest t such that all suffixes of w have pairwise different sets of subsequences of length at most t.	Hard8	StringGreedy+1	No attempts yet	0.5s	2048 MB	Judgeable
Interstellar IntervalsCount the colorings of N points that match an R, B, X pattern, where each coloring is built from disjoint blocks of x red points followed by x blue points.	Hard8	Dynamic programmingString matching	No attempts yet	2s	2048 MB	Judgeable
Sorting MachineGiven N equal-length texts, each query asks for the sorted position of text X among texts A to B, after keeping only columns L to R and sorting stably.	Hard8	StringSorting+2	No attempts yet	1.5s	2048 MB	Judgeable
Interesting WordsCount the ordered sequences of given words whose concatenation is a palindrome of exact length L, modulo 1e9+7.	Hard8	Dynamic programmingString matching+1	No attempts yet	3s	2048 MB	Judgeable
Palindrome StringsGiven a string S and query strings t, count the pairs (l, r) for which t followed by S[l..r] is a palindrome.	Hard8	String matchingString	No attempts yet	2s	2048 MB	Judgeable
Sending SubstringsGiven team names, count over all ordered pairs of different teams the distinct substrings that both names contain, summed over every pair.	Hard8	String matchingString+1	No attempts yet	6s	2048 MB	Judgeable
Shom LanguageGiven a sentence with alternating uppercase and lowercase letters, find the minimum number of distinct two-letter words needed to rebuild it via overlapping placements.	Hard9	GraphCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
All Closed-Walk LengthsGiven a directed graph, decide for every length x whether a closed walk of that length exists, then print the eventually periodic 0/1 sequence in its shortest prefix-plus-period notation.	Hard9	GraphMatrix+2	No attempts yet	2s	128 MB	Judgeable
Shom CodeGiven binary codes assigned to up to 26 letters, find the minimum length of a binary string decodable as three or more distinct letter sequences, or -1 if none exists.	Hard9	TrieBFS+2	No attempts yet	2s	128 MB	Judgeable
Hangul-Missing NumbersGiven which Hangul letters are forbidden, find the N-th positive integer up to 10^52-1 whose Korean numeral representation avoids all forbidden jamo, using digit DP over decomposed syllables.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Hard MatchingGiven a text sequence and two number patterns, count positions where consecutive-sum grouping matches each pattern, then find the smallest glue value x maximizing matches of the concatenated pattern with x inserted between them and report that match count.	Hard9	String matchingPrefix sum+2	No attempts yet	30s	1536 MB	Judgeable
Casting SpellsGiven a string, find the maximum length of a substring of the form ww^R w w^R (a palindrome ww^R followed immediately by itself) across up to 40 large test cases.	Hard9	String matchingString+2	No attempts yet	1s	128 MB	Judgeable
K’ak’-u-pakal and the Maya ScriptParse a recursive grammar for Maya glyph compositions and render a minimal-size ASCII-art box layout respecting horizontal/vertical grouping and bracket-doubling size rules.	Hard9	RecursionString+2	No attempts yet	1s	128 MB	Judgeable
OutsourcingGiven two directed labeled graphs (factories) with start and final nodes, decide whether the two sets of label sequences realizable as paths from start to final are identical.	Hard9	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
The Most Powerful SpellGiven a labeled directed graph, find the lexicographically smallest string that labels a walk from the star node to the gold node, or print NO if none exists or the minimum is unbounded.	Hard9	GraphShortest path+2	No attempts yet	5s	128 MB	Judgeable
Old MemoriesGiven pieces of an original text and an altered copy with at most d edits, list all original strings whose edit distance to the copy is at most d and where every position lies inside some piece occurrence.	Hard9	String matchingDynamic programming+2	No attempts yet	10s	128 MB	Judgeable
ContactGiven a binary string and a length range [A,B], report the N largest occurrence counts and all patterns achieving each count, with output ordering rules.	Hard9	StringSorting+2	No attempts yet	1s	128 MB	Judgeable
Version-Controlled IDEMaintain a versioned text buffer under insert and delete operations, answering substring queries against any past version, with all commands encoded by a running counter.	Hard9	TreeImplementation+2	No attempts yet	1s	128 MB	Judgeable
Synnerg LifeformGiven rewriting rules that merge adjacent synnergs with multiplicative lifetimes, find all maximum-lifetime synnergs obtainable by fully unifying some contiguous block of each input sequence.	Hard9	Dynamic programmingIntervals+2	No attempts yet	1s	128 MB	Judgeable
JukeboxEach song has a title and artist; decide which artist fields to drop so the total length of shortest unique substrings over all title and remaining artist strings is minimized.	Hard9	StringBrute force+2	No attempts yet	3s	128 MB	Judgeable
ExamGiven each student's distribution over exam scores, find the exact probability that the sequence of European marks from all students avoids every listed unpleasant string.	Hard9	Dynamic programmingString matching+2	No attempts yet	2s	128 MB	Judgeable
PurifyRepeatedly delete forbidden substrings from P, always choosing the earliest-ending occurrence and removing the shortest such forbidden word, then print what remains.	Hard9	StringTrie+2	No attempts yet	1s	64 MB	Judgeable
Accountant NotesFor each note, find every starting row in the summary file where a renamed transcription of the note appears as consecutive rows.	Hard9	String matchingHash map+2	No attempts yet	5s	512 MB	Judgeable
Suffix Array ReconstructionGiven a permutation p, decide whether it is the suffix array of some lowercase string and, if so, output the lexicographically smallest such string.	Hard9	StringGreedy+2	No attempts yet	1s	512 MB	Judgeable
Axes of SymmetryFor each simple polygon, count its axes of symmetry; n can reach 100000, so the check must run in near-linear time.	Hard9	String matchingGeometry+2	No attempts yet	1s	128 MB	Judgeable
Isles in a Triangular GridEnumerate all non-congruent triangular-grid isles of up to ten triangles, canonicalizing each by the lexicographically smallest clockwise boundary-turn word.	Hard9	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
The CodeGiven a prefix code entered via button presses, find the code words that resynchronize decoding after any loss of leading bits.	Hard9	TrieString+2	No attempts yet	1s	128 MB	Judgeable
HamstersFind the shortest lowercase string containing at least m occurrences of the given hamster names, counted with multiplicity.	Hard9	String matchingDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
PeriodicityFor each name, find the lexicographically smallest bit string of the same length whose set of periods equals the name's set of periods, or XXX if none exists.	Hard9	StringPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Computational BiologyFor each query length m, find a length-m word whose every cyclic rotation appears in s, maximizing the total count of those rotations in s.	Hard9	StringSorting+2	No attempts yet	5s	128 MB	Judgeable
FragmentsCount how many times each digit string appears as a contiguous substring across the decimal forms of all numbers in a union of disjoint integer intervals up to 10^18.	Hard9	String matchingDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Quasi-templateCount the distinct words that, as substrings of v with possibly overhanging copies, can tile across the whole input; report the count and the shortest, lexicographically smallest such word.	Hard9	String matchingString+2	No attempts yet	1s	128 MB	Judgeable
Fibonacci WordCount occurrences of a given binary pattern in the Fibonacci word F_m and count distinct subwords occurring at least that many times, mod 20062006, with m up to 1e9.	Hard9	StringDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Prefix-SuffixesCount proper borders summed over all substrings of a given lowercase word of length up to 10^5.	Hard9	String matchingString+1	No attempts yet	1s	128 MB	Judgeable
Minimum bracketsGiven an arithmetic template with holes, delete as many brackets as possible while keeping the same value for every valid assignment of real numbers to the holes.	Hard9	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
Palindromic EquivalenceCount words of the same length that have palindromic substrings at exactly the same positions as the given word.	Hard9	StringString matching+2	No attempts yet	1s	128 MB	Judgeable
PuzzleBuild the longest string over the first n capital letters that avoids all forbidden substrings, or print No when no maximum exists.	Hard9	String matchingTrie+2	No attempts yet	1s	128 MB	Judgeable