String Problems
699 String LeetCode problems · Browse tasks by difficulty and choose your next practice problem.
Learn the coding interview patterns behind these problems.
Start with these
3 Longest Substring Without Repeating Characters Medium5 Longest Palindromic Substring Medium13 Roman to Integer Easy14 Longest Common Prefix Easy20 Valid Parentheses Easy49 Group Anagrams Medium76 Minimum Window Substring Hard79 Word Search Medium91 Decode Ways Medium125 Valid Palindrome Easy139 Word Break Medium208 Implement Trie (Prefix Tree) Medium211 Design Add and Search Words Data Structure Medium212 Word Search II Hard242 Valid Anagram Easy297 Serialize and Deserialize Binary Tree Hard412 Fizz Buzz Easy424 Longest Repeating Character Replacement Medium539 Minimum Time Difference Medium647 Palindromic Substrings Medium804 Unique Morse Code Words Easy929 Unique Email Addresses Easy1143 Longest Common Subsequence Medium1763 Longest Nice Substring Easy2325 Decode the Message Easy3120 Count the Number of Special Characters I Easy3228 Maximum Number of Operations to Move Ones to the End Medium3291 Minimum Number of Valid Strings to Form Target I Medium3292 Minimum Number of Valid Strings to Form Target II Hard3303 Find the Occurrence of First Almost Equal Substring Hard3320 Count The Number of Winning Sequences Hard3327 Check if DFS Strings Are Palindromes Hard3348 Smallest Divisible Digit Product II Hard3614 Process String with Special Operations II Hard3615 Longest Palindromic Path in Graph Hard
All String problems
3 Longest Substring Without Repeating Characters Medium5 Longest Palindromic Substring Medium6 Zigzag Conversion Medium8 String to Integer (atoi) Medium10 Regular Expression Matching Hard12 Integer to Roman Medium13 Roman to Integer Easy14 Longest Common Prefix Easy17 Letter Combinations of a Phone Number Medium20 Valid Parentheses Easy22 Generate Parentheses Medium28 Find the Index of the First Occurrence in a String Easy30 Substring with Concatenation of All Words Hard32 Longest Valid Parentheses Hard38 Count and Say Medium43 Multiply Strings Medium44 Wildcard Matching Hard49 Group Anagrams Medium58 Length of Last Word Easy65 Valid Number Hard67 Add Binary Easy68 Text Justification Hard71 Simplify Path Medium72 Edit Distance Medium76 Minimum Window Substring Hard79 Word Search Medium87 Scramble String Hard91 Decode Ways Medium93 Restore IP Addresses Medium97 Interleaving String Medium115 Distinct Subsequences Hard125 Valid Palindrome Easy126 Word Ladder II Hard127 Word Ladder Hard131 Palindrome Partitioning Medium132 Palindrome Partitioning II Hard139 Word Break Medium140 Word Break II Hard151 Reverse Words in a String Medium165 Compare Version Numbers Medium166 Fraction to Recurring Decimal Medium168 Excel Sheet Column Title Easy171 Excel Sheet Column Number Easy179 Largest Number Medium187 Repeated DNA Sequences Medium205 Isomorphic Strings Easy208 Implement Trie (Prefix Tree) Medium211 Design Add and Search Words Data Structure Medium212 Word Search II Hard214 Shortest Palindrome Hard224 Basic Calculator Hard227 Basic Calculator II Medium241 Different Ways to Add Parentheses Medium242 Valid Anagram Easy257 Binary Tree Paths Easy273 Integer to English Words Hard282 Expression Add Operators Hard290 Word Pattern Easy297 Serialize and Deserialize Binary Tree Hard299 Bulls and Cows Medium301 Remove Invalid Parentheses Hard306 Additive Number Medium316 Remove Duplicate Letters Medium318 Maximum Product of Word Lengths Medium331 Verify Preorder Serialization of a Binary Tree Medium336 Palindrome Pairs Hard344 Reverse String Easy345 Reverse Vowels of a String Easy383 Ransom Note Easy385 Mini Parser Medium387 First Unique Character in a String Easy388 Longest Absolute File Path Medium389 Find the Difference Easy392 Is Subsequence Easy394 Decode String Medium395 Longest Substring with At Least K Repeating Characters Medium399 Evaluate Division Medium402 Remove K Digits Medium405 Convert a Number to Hexadecimal Easy409 Longest Palindrome Easy412 Fizz Buzz Easy415 Add Strings Easy420 Strong Password Checker Hard423 Reconstruct Original Digits from English Medium424 Longest Repeating Character Replacement Medium433 Minimum Genetic Mutation Medium434 Number of Segments in a String Easy438 Find All Anagrams in a String Medium443 String Compression Medium449 Serialize and Deserialize BST Medium451 Sort Characters By Frequency Medium459 Repeated Substring Pattern Easy466 Count The Repetitions Hard467 Unique Substrings in Wraparound String Medium468 Validate IP Address Medium472 Concatenated Words Hard474 Ones and Zeroes Medium481 Magical String Medium482 License Key Formatting Easy488 Zuma Game Hard500 Keyboard Row Easy504 Base 7 Easy514 Freedom Trail Hard516 Longest Palindromic Subsequence Medium520 Detect Capital Easy521 Longest Uncommon Subsequence I Easy522 Longest Uncommon Subsequence II Medium524 Longest Word in Dictionary through Deleting Medium535 Encode and Decode TinyURL Medium537 Complex Number Multiplication Medium539 Minimum Time Difference Medium541 Reverse String II Easy551 Student Attendance Record I Easy556 Next Greater Element III Medium557 Reverse Words in a String III Easy564 Find the Closest Palindrome Hard567 Permutation in String Medium583 Delete Operation for Two Strings Medium591 Tag Validator Hard592 Fraction Addition and Subtraction Medium599 Minimum Index Sum of Two Lists Easy606 Construct String from Binary Tree Medium609 Find Duplicate File in System Medium639 Decode Ways II Hard640 Solve the Equation Medium647 Palindromic Substrings Medium648 Replace Words Medium649 Dota2 Senate Medium657 Robot Return to Origin Easy664 Strange Printer Hard676 Implement Magic Dictionary Medium677 Map Sum Pairs Medium678 Valid Parenthesis String Medium680 Valid Palindrome II Easy686 Repeated String Match Medium691 Stickers to Spell Word Hard692 Top K Frequent Words Medium696 Count Binary Substrings Easy709 To Lower Case Easy712 Minimum ASCII Delete Sum for Two Strings Medium720 Longest Word in Dictionary Medium721 Accounts Merge Medium722 Remove Comments Medium726 Number of Atoms Hard730 Count Different Palindromic Subsequences Hard736 Parse Lisp Expression Hard745 Prefix and Suffix Search Hard748 Shortest Completing Word Easy752 Open the Lock Medium761 Special Binary String Hard763 Partition Labels Medium767 Reorganize String Medium770 Basic Calculator IV Hard771 Jewels and Stones Easy777 Swap Adjacent in LR String Medium784 Letter Case Permutation Medium791 Custom Sort String Medium792 Number of Matching Subsequences Medium796 Rotate String Easy804 Unique Morse Code Words Easy806 Number of Lines To Write String Easy809 Expressive Words Medium811 Subdomain Visit Count Medium816 Ambiguous Coordinates Medium819 Most Common Word Easy820 Short Encoding of Words Medium821 Shortest Distance to a Character Easy824 Goat Latin Easy828 Count Unique Characters of All Substrings of a Given String Hard830 Positions of Large Groups Easy831 Masking Personal Information Medium833 Find And Replace in String Medium838 Push Dominoes Medium839 Similar String Groups Hard842 Split Array into Fibonacci Sequence Medium843 Guess the Word Hard844 Backspace String Compare Easy848 Shifting Letters Medium854 K-Similar Strings Hard856 Score of Parentheses Medium859 Buddy Strings Easy880 Decoded String at Index Medium884 Uncommon Words from Two Sentences Easy890 Find and Replace Pattern Medium893 Groups of Special-Equivalent Strings Medium899 Orderly Queue Hard902 Numbers At Most N Given Digit Set Hard903 Valid Permutations for DI Sequence Hard906 Super Palindromes Hard916 Word Subsets Medium917 Reverse Only Letters Easy921 Minimum Add to Make Parentheses Valid Medium925 Long Pressed Name Easy926 Flip String to Monotone Increasing Medium929 Unique Email Addresses Easy936 Stamping The Sequence Hard937 Reorder Data in Log Files Medium940 Distinct Subsequences II Hard942 DI String Match Easy943 Find the Shortest Superstring Hard944 Delete Columns to Make Sorted Easy949 Largest Time for Given Digits Medium953 Verifying an Alien Dictionary Easy955 Delete Columns to Make Sorted II Medium960 Delete Columns to Make Sorted III Hard966 Vowel Spellchecker Medium972 Equal Rational Numbers Hard981 Time Based Key-Value Store Medium984 String Without AAA or BBB Medium988 Smallest String Starting From Leaf Medium990 Satisfiability of Equality Equations Medium1002 Find Common Characters Easy1003 Check If Word Is Valid After Substitutions Medium1016 Binary String With Substrings Representing 1 To N Medium1021 Remove Outermost Parentheses Easy1023 Camelcase Matching Medium1028 Recover a Tree From Preorder Traversal Hard1032 Stream of Characters Hard1041 Robot Bounded In Circle Medium1044 Longest Duplicate Substring Hard1047 Remove All Adjacent Duplicates In String Easy1048 Longest String Chain Medium1061 Lexicographically Smallest Equivalent String Medium1071 Greatest Common Divisor of Strings Easy1078 Occurrences After Bigram Easy1079 Letter Tile Possibilities Medium1081 Smallest Subsequence of Distinct Characters Medium1092 Shortest Common Supersequence Hard1096 Brace Expansion II Hard1106 Parsing A Boolean Expression Hard1108 Defanging an IP Address Easy1111 Maximum Nesting Depth of Two Valid Parentheses Strings Medium1138 Alphabet Board Path Medium1143 Longest Common Subsequence Medium1147 Longest Chunked Palindrome Decomposition Hard1154 Day of the Year Easy1156 Swap For Longest Repeated Character Substring Medium1160 Find Words That Can Be Formed by Characters Easy1163 Last Substring in Lexicographical Order Hard1169 Invalid Transactions Medium1170 Compare Strings by Frequency of the Smallest Character Medium1177 Can Make Palindrome from Substring Medium1178 Number of Valid Words for Each Puzzle Hard1189 Maximum Number of Balloons Easy1190 Reverse Substrings Between Each Pair of Parentheses Medium1202 Smallest String With Swaps Medium1208 Get Equal Substrings Within Budget Medium1209 Remove All Adjacent Duplicates in String II Medium1221 Split a String in Balanced Strings Easy1233 Remove Sub-Folders from the Filesystem Medium1234 Replace the Substring for Balanced String Medium1239 Maximum Length of a Concatenated String with Unique Characters Medium1247 Minimum Swaps to Make Strings Equal Medium1249 Minimum Remove to Make Valid Parentheses Medium1255 Maximum Score Words Formed by Letters Hard1268 Search Suggestions System Medium1278 Palindrome Partitioning III Hard1286 Iterator for Combination Medium1297 Maximum Number of Occurrences of a Substring Medium1307 Verbal Arithmetic Puzzle Hard1309 Decrypt String from Alphabet to Integer Mapping Easy1312 Minimum Insertion Steps to Make a String Palindrome Hard1316 Distinct Echo Substrings Hard1320 Minimum Distance to Type a Word Using Two Fingers Hard1324 Print Words Vertically Medium1328 Break a Palindrome Medium1332 Remove Palindromic Subsequences Easy1347 Minimum Number of Steps to Make Two Strings Anagram Medium1358 Number of Substrings Containing All Three Characters Medium1360 Number of Days Between Two Dates Easy1366 Rank Teams by Votes Medium1370 Increasing Decreasing String Easy1371 Find the Longest Substring Containing Vowels in Even Counts Medium1374 Generate a String With Characters That Have Odd Counts Easy1392 Longest Happy Prefix Hard1396 Design Underground System Medium1397 Find All Good Strings Hard1400 Construct K Palindrome Strings Medium1404 Number of Steps to Reduce a Number in Binary Representation to One Medium1405 Longest Happy String Medium1408 String Matching in an Array Easy1410 HTML Entity Parser Medium1415 The k-th Lexicographical String of All Happy Strings of Length n Medium1416 Restore The Array Hard1417 Reformat The String Easy1418 Display Table of Food Orders in a Restaurant Medium1419 Minimum Number of Frogs Croaking Medium1422 Maximum Score After Splitting a String Easy1433 Check If a String Can Break Another String Medium1436 Destination City Easy1446 Consecutive Characters Easy1447 Simplified Fractions Medium1451 Rearrange Words in a Sentence Medium1452 People Whose List of Favorite Companies Is Not a Subset of Another List Medium1455 Check If a Word Occurs As a Prefix of Any Word in a Sentence Easy1456 Maximum Number of Vowels in a Substring of Given Length Medium1461 Check If a String Contains All Binary Codes of Size K Medium1487 Making File Names Unique Medium1496 Path Crossing Easy1505 Minimum Possible Integer After at Most K Adjacent Swaps On Digits Hard1507 Reformat Date Easy1513 Number of Substrings With Only 1s Medium1520 Maximum Number of Non-Overlapping Substrings Hard1525 Number of Good Ways to Split a String Medium1528 Shuffle String Easy1529 Minimum Suffix Flips Medium1531 String Compression II Hard1540 Can Convert String in K Moves Medium1541 Minimum Insertions to Balance a Parentheses String Medium1542 Find Longest Awesome Substring Hard1544 Make The String Great Easy1545 Find Kth Bit in Nth Binary String Medium1556 Thousand Separator Easy1573 Number of Ways to Split a String Medium1576 Replace All ?'s to Avoid Consecutive Repeating Characters Easy1578 Minimum Time to Make Rope Colorful Medium1585 Check If String Is Transformable With Substring Sort Operations Hard1592 Rearrange Spaces Between Words Easy1593 Split a String Into the Max Number of Unique Substrings Medium1598 Crawler Log Folder Easy1604 Alert Using Same Key-Card Three or More Times in a One Hour Period Medium1614 Maximum Nesting Depth of the Parentheses Easy1616 Split Two Strings to Make Palindrome Medium1624 Largest Substring Between Two Equal Characters Easy1625 Lexicographically Smallest String After Applying Operations Medium1629 Slowest Key Easy1638 Count Substrings That Differ by One Character Medium1639 Number of Ways to Form a Target String Given a Dictionary Hard1647 Minimum Deletions to Make Character Frequencies Unique Medium1653 Minimum Deletions to Make String Balanced Medium1657 Determine if Two Strings Are Close Medium1662 Check If Two String Arrays are Equivalent Easy1663 Smallest String With A Given Numeric Value Medium1668 Maximum Repeating Substring Easy1678 Goal Parser Interpretation Easy1684 Count the Number of Consistent Strings Easy1689 Partitioning Into Minimum Number Of Deci-Binary Numbers Medium1694 Reformat Phone Number Easy1702 Maximum Binary String After Change Medium1704 Determine if String Halves Are Alike Easy1717 Maximum Score From Removing Substrings Medium1736 Latest Time by Replacing Hidden Digits Easy1737 Change Minimum Characters to Satisfy One of Three Conditions Medium1745 Palindrome Partitioning IV Hard1750 Minimum Length of String After Deleting Similar Ends Medium1754 Largest Merge Of Two Strings Medium1758 Minimum Changes To Make Alternating Binary String Easy1759 Count Number of Homogenous Substrings Medium1763 Longest Nice Substring Easy1768 Merge Strings Alternately Easy1769 Minimum Number of Operations to Move All Balls to Each Box Medium1771 Maximize Palindrome Length From Subsequences Hard1773 Count Items Matching a Rule Easy1781 Sum of Beauty of All Substrings Medium1784 Check if Binary String Has at Most One Segment of Ones Easy1790 Check if One String Swap Can Make Strings Equal Easy1796 Second Largest Digit in a String Easy1805 Number of Different Integers in a String Easy1807 Evaluate the Bracket Pairs of a String Medium1812 Determine Color of a Chessboard Square Easy1813 Sentence Similarity III Medium1816 Truncate Sentence Easy1830 Minimum Number of Operations to Make String Sorted Hard1832 Check if the Sentence Is Pangram Easy1839 Longest Substring Of All Vowels in Order Medium1844 Replace All Digits with Characters Easy1849 Splitting a String Into Descending Consecutive Values Medium1850 Minimum Adjacent Swaps to Reach the Kth Smallest Number Medium1859 Sorting the Sentence Easy1864 Minimum Number of Swaps to Make the Binary String Alternating Medium1869 Longer Contiguous Segments of Ones than Zeros Easy1871 Jump Game VII Medium1876 Substrings of Size Three with Distinct Characters Easy1880 Check if Word Equals Summation of Two Words Easy1881 Maximum Value after Insertion Medium1888 Minimum Number of Flips to Make the Binary String Alternating Medium1896 Minimum Cost to Change the Final Value of Expression Hard1897 Redistribute Characters to Make All Strings Equal Easy1898 Maximum Number of Removable Characters Medium1903 Largest Odd Number in String Easy1904 The Number of Full Rounds You Have Played Medium1910 Remove All Occurrences of a Substring Medium1915 Number of Wonderful Substrings Medium1927 Sum Game Medium1930 Unique Length-3 Palindromic Subsequences Medium1935 Maximum Number of Words You Can Type Easy1941 Check if All Characters Have Equal Number of Occurrences Easy1945 Sum of Digits of String After Convert Easy1946 Largest Number After Mutating Substring Medium1948 Delete Duplicate Folders in System Hard1957 Delete Characters to Make Fancy String Easy1960 Maximum Product of the Length of Two Palindromic Substrings Hard1961 Check If String Is a Prefix of Array Easy1963 Minimum Number of Swaps to Make the String Balanced Medium1967 Number of Strings That Appear as Substrings in Word Easy1974 Minimum Time to Type Word Using Special Typewriter Easy1977 Number of Ways to Separate Numbers Hard1980 Find Unique Binary String Medium1985 Find the Kth Largest Integer in the Array Medium1987 Number of Unique Good Subsequences Hard2000 Reverse Prefix of Word Easy2002 Maximum Product of the Length of Two Palindromic Subsequences Medium2011 Final Value of Variable After Performing Operations Easy2014 Longest Subsequence Repeated k Times Hard2019 The Score of Students Solving Math Expression Hard2023 Number of Pairs of Strings With Concatenation Equal to Target Medium2024 Maximize the Confusion of an Exam Medium2027 Minimum Moves to Convert String Easy2030 Smallest K-Length Subsequence With Occurrences of a Letter Hard2038 Remove Colored Pieces if Both Neighbors are the Same Color Medium2042 Check if Numbers Are Ascending in a Sentence Easy2047 Number of Valid Words in a Sentence Easy2053 Kth Distinct String in an Array Easy2055 Plates Between Candles Medium2056 Number of Valid Move Combinations On Chessboard Hard2060 Check if an Original String Exists Given Two Encoded Strings Hard2062 Count Vowel Substrings of a String Easy2063 Vowels of All Substrings Medium2068 Check Whether Two Strings are Almost Equivalent Easy2075 Decode the Slanted Ciphertext Medium2085 Count Common Words With One Occurrence Easy2086 Minimum Number of Food Buckets to Feed the Hamsters Medium2096 Step-By-Step Directions From a Binary Tree Node to Another Medium2103 Rings and Rods Easy2108 Find First Palindromic String in the Array Easy2109 Adding Spaces to a String Medium2114 Maximum Number of Words Found in Sentences Easy2115 Find All Possible Recipes from Given Supplies Medium2116 Check if a Parentheses String Can Be Valid Medium2120 Execution of All Suffix Instructions Staying in a Grid Medium2124 Check if All A's Appears Before All B's Easy2125 Number of Laser Beams in a Bank Medium2129 Capitalize the Title Easy2131 Longest Palindrome by Concatenating Two Letter Words Medium2135 Count Words Obtained After Adding a Letter Medium2138 Divide a String Into Groups of Size k Easy2147 Number of Ways to Divide a Long Corridor Hard2156 Find Substring With Given Hash Value Hard2157 Groups of Strings Hard2166 Design Bitset Medium2167 Minimum Time to Remove All Cars Containing Illegal Goods Hard2182 Construct String With Repeat Limit Medium2185 Counting Words With a Given Prefix Easy2186 Minimum Number of Steps to Make Two Strings Anagram II Medium2193 Minimum Number of Moves to Make Palindrome Hard2194 Cells in a Range on an Excel Sheet Easy2207 Maximize Number of Subsequences in a String Medium2209 Minimum White Tiles After Covering With Carpets Hard2211 Count Collisions on a Road Medium2213 Longest Substring of One Repeating Character Hard2222 Number of Ways to Select Buildings Medium2223 Sum of Scores of Built Strings Hard2224 Minimum Number of Operations to Convert Time Easy2227 Encrypt and Decrypt Strings Hard2232 Minimize Result by Adding Parentheses to Expression Medium2243 Calculate Digit Sum of a String Easy2246 Longest Path With Different Adjacent Characters Hard2255 Count Prefixes of a Given String Easy2259 Remove Digit From Number to Maximize Result Easy2262 Total Appeal of A String Hard2264 Largest 3-Same-Digit Number in String Easy2266 Count Number of Texts Medium2269 Find the K-Beauty of a Number Easy2273 Find Resultant Array After Removing Anagrams Easy2278 Percentage of Letter in String Easy2283 Check if Number Has Equal Digit Count and Digit Value Easy2284 Sender With Largest Word Count Medium2287 Rearrange Characters to Make Target String Easy2288 Apply Discount to Prices Medium2296 Design a Text Editor Hard2299 Strong Password Checker II Easy2301 Match Substring After Replacement Hard2306 Naming a Company Hard2309 Greatest English Letter in Upper and Lower Case Easy2311 Longest Binary Subsequence Less Than or Equal to K Medium2315 Count Asterisks Easy2325 Decode the Message Easy2337 Move Pieces to Obtain a String Medium2343 Query Kth Smallest Trimmed Number Medium2351 First Letter to Appear Twice Easy2353 Design a Food Rating System Medium2370 Longest Ideal Subsequence Medium2375 Construct Smallest Number From DI String Medium2379 Minimum Recolors to Get K Consecutive Black Blocks Easy2380 Time Needed to Rearrange a Binary String Medium2381 Shifting Letters II Medium2384 Largest Palindromic Number Medium2390 Removing Stars From a String Medium2391 Minimum Amount of Time to Collect Garbage Medium2399 Check Distances Between Same Letters Easy2405 Optimal Partition of String Medium2409 Count Days Spent Together Easy2414 Length of the Longest Alphabetical Continuous Substring Medium2416 Sum of Prefix Scores of Strings Hard2418 Sort the People Easy2423 Remove Letter To Equalize Frequency Easy2430 Maximum Deletions on a String Hard2434 Using a Robot to Print the Lexicographically Smallest String Medium2437 Number of Valid Clock Times Easy2446 Determine if Two Events Have Conflict Easy2451 Odd String Difference Easy2452 Words Within Two Edits of Dictionary Medium2456 Most Popular Video Creator Medium2468 Split Message Based on Limit Hard2472 Maximum Number of Non-overlapping Palindrome Substrings Hard2478 Number of Beautiful Partitions Hard2483 Minimum Penalty for a Shop Medium2484 Count Palindromic Subsequences Hard2486 Append Characters to String to Make Subsequence Medium2490 Circular Sentence Easy2496 Maximum Value of a String in an Array Easy2506 Count Pairs Of Similar Strings Easy2512 Reward Top K Students Medium2514 Count Anagrams Hard2515 Shortest Distance to Target String in a Circular Array Easy2516 Take K of Each Character From Left and Right Medium2522 Partition String Into Substrings With Values at Most K Medium2531 Make Number of Distinct Characters Equal Medium2546 Apply Bitwise Operations to Make Strings Equal Medium2559 Count Vowel Strings in Ranges Medium2564 Substring XOR Queries Medium2565 Subsequence With the Minimum Score Hard2573 Find the String with LCP Hard2575 Find the Divisibility Array of a String Medium2586 Count the Number of Vowel Strings in Range Easy2606 Find the Substring With Maximum Cost Medium2609 Find the Longest Balanced Substring of a Binary String Easy2645 Minimum Additions to Make Valid String Medium2663 Lexicographically Smallest Beautiful String Hard2678 Number of Senior Citizens Easy2696 Minimum String Length After Removing Substrings Easy2697 Lexicographically Smallest Palindrome Easy2707 Extra Characters in a String Medium2710 Remove Trailing Zeros From a String Easy2712 Minimum Cost to Make All Characters Equal Medium2716 Minimize String Length Easy2719 Count of Integers Hard2730 Find the Longest Semi-Repetitive Substring Medium2734 Lexicographically Smallest String After Substring Operation Medium2744 Find Maximum Number of String Pairs Easy2746 Decremental String Concatenation Medium2767 Partition String Into Minimum Beautiful Substrings Medium2781 Length of the Longest Valid Substring Hard2785 Sort Vowels in a String Medium2788 Split Strings by Separator Easy2800 Shortest String That Contains Three Strings Medium2801 Count Stepping Numbers in Range Hard2810 Faulty Keyboard Easy2825 Make String a Subsequence Using Cyclic Increments Medium2828 Check if a String Is an Acronym of Words Easy2833 Furthest Point From Origin Easy2839 Check if Strings Can be Made Equal With Operations I Easy2840 Check if Strings Can be Made Equal With Operations II Medium2842 Count K-Subsequences of a String With Maximum Beauty Hard2844 Minimum Operations to Make a Special Number Medium2851 String Transformation Hard2864 Maximum Odd Binary Number Easy2896 Apply Operations to Make Two Strings Equal Medium2900 Longest Unequal Adjacent Groups Subsequence I Easy2901 Longest Unequal Adjacent Groups Subsequence II Medium2904 Shortest and Lexicographically Smallest Beautiful String Medium2911 Minimum Changes to Make K Semi-palindromes Hard2914 Minimum Number of Changes to Make Binary String Beautiful Medium2933 High-Access Employees Medium2937 Make Three Strings Equal Easy2938 Separate Black and White Balls Medium2942 Find Words Containing Character Easy2947 Count Beautiful Substrings I Medium2949 Count Beautiful Substrings II Hard2953 Count Complete Substrings Hard2957 Remove Adjacent Almost-Equal Characters Medium2976 Minimum Cost to Convert String I Medium2977 Minimum Cost to Convert String II Hard2981 Find Longest Special Substring That Occurs Thrice I Medium2982 Find Longest Special Substring That Occurs Thrice II Medium2983 Palindrome Rearrangement Queries Hard2999 Count the Number of Powerful Integers Hard3003 Maximize the Number of Partitions After Operations Hard3006 Find Beautiful Indices in the Given Array I Medium3008 Find Beautiful Indices in the Given Array II Hard3014 Minimum Number of Pushes to Type Word I Easy3016 Minimum Number of Pushes to Type Word II Medium3019 Number of Changing Keys Easy3029 Minimum Time to Revert Word to Initial State I Medium3031 Minimum Time to Revert Word to Initial State II Hard3035 Maximum Palindromes After Operations Medium3042 Count Prefix and Suffix Pairs I Easy3043 Find the Length of the Longest Common Prefix Medium3045 Count Prefix and Suffix Pairs II Hard3076 Shortest Uncommon Substring in an Array Medium3081 Replace Question Marks in String to Minimize Its Value Medium3083 Existence of a Substring in a String and Its Reverse Easy3084 Count Substrings Starting and Ending with Given Character Medium3085 Minimum Deletions to Make String K-Special Medium3090 Maximum Length Substring With Two Occurrences Easy3093 Longest Common Suffix Queries Hard3106 Lexicographically Smallest String After Operations With Constraint Medium3110 Score of a String Easy3114 Latest Time You Can Obtain After Replacing Characters Easy3120 Count the Number of Special Characters I Easy3121 Count the Number of Special Characters II Medium3136 Valid Word Easy3137 Minimum Number of Operations to Make Word K-Periodic Medium3138 Minimum Length of Anagram Concatenation Medium3143 Maximum Points Inside the Square Medium3144 Minimum Substring Partition of Equal Character Frequency Medium3146 Permutation Difference between Two Strings Easy3163 String Compression III Medium3168 Minimum Number of Chairs in a Waiting Room Easy3170 Lexicographically Minimum String After Removing Stars Medium3174 Clear Digits Easy3210 Find the Encrypted String Easy3211 Generate Binary Strings Without Adjacent Zeros Medium3213 Construct String with Minimum Cost Hard3216 Lexicographically Smallest String After a Swap Easy3223 Minimum Length of String After Operations Medium3227 Vowels Game in a String Medium3228 Maximum Number of Operations to Move Ones to the End Medium3234 Count the Number of Substrings With Dominant Ones Medium3248 Snake in Matrix Easy3258 Count Substrings That Satisfy K-Constraint I Easy3260 Find the Largest Palindrome Divisible by K Hard3261 Count Substrings That Satisfy K-Constraint II Hard3271 Hash Divided String Medium3274 Check if Two Chessboard Squares Have the Same Color Easy3280 Convert Date to Binary Easy3291 Minimum Number of Valid Strings to Form Target I Medium3292 Minimum Number of Valid Strings to Form Target II Hard3295 Report Spam Message Medium3297 Count Substrings That Can Be Rearranged to Contain a String I Medium3298 Count Substrings That Can Be Rearranged to Contain a String II Hard3302 Find the Lexicographically Smallest Valid Sequence Medium3303 Find the Occurrence of First Almost Equal Substring Hard3305 Count of Substrings Containing Every Vowel and K Consonants I Medium3306 Count of Substrings Containing Every Vowel and K Consonants II Medium3316 Find Maximum Removals From Source String Medium3320 Count The Number of Winning Sequences Hard3324 Find the Sequence of Strings Appeared on the Screen Medium3325 Count Substrings With K-Frequency Characters I Medium3327 Check if DFS Strings Are Palindromes Hard3330 Find the Original Typed String I Easy3331 Find Subtree Sizes After Changes Medium3333 Find the Original Typed String II Hard3335 Total Characters in String After Transformations I Medium3337 Total Characters in String After Transformations II Hard3340 Check Balanced String Easy3343 Count Number of Balanced Permutations Hard3348 Smallest Divisible Digit Product II Hard3352 Count K-Reducible Numbers Less Than N Hard3361 Shift Distance Between Two Strings Medium3365 Rearrange K Substrings to Form Target String Medium3387 Maximize Amount After Two Days of Conversions Medium3389 Minimum Operations to Make Character Frequencies Equal Hard3399 Smallest Substring With Identical Characters II Hard3403 Find the Lexicographically Largest String From the Box I Medium3407 Substring Matching Pattern Easy3412 Find Mirror Score of a String Medium3435 Frequencies of Shortest Supersequences Hard3438 Find Valid Pair of Adjacent Digits in String Easy3441 Minimum Cost Good Caption Hard3442 Maximum Difference Between Even and Odd Frequency I Easy3443 Maximum Manhattan Distance After K Changes Medium3445 Maximum Difference Between Even and Odd Frequency II Hard3448 Count Substrings Divisible By Last Digit Hard3455 Shortest Matching Substring Hard3456 Find Special Substring of Length K Easy3458 Select K Disjoint Special Substrings Medium3461 Check If Digits Are Equal in String After Operations I Easy3463 Check If Digits Are Equal in String After Operations II Hard3472 Longest Palindromic Subsequence After at Most K Operations Medium3474 Lexicographically Smallest Generated String Hard3484 Design Spreadsheet Medium3485 Longest Common Prefix of K Strings After Removal Hard3498 Reverse Degree of a String Easy3499 Maximize Active Section with Trade I Medium3501 Maximize Active Section with Trade II Hard3503 Longest Palindrome After Substring Concatenation I Medium3504 Longest Palindrome After Substring Concatenation II Hard3517 Smallest Palindromic Rearrangement I Medium3518 Smallest Palindromic Rearrangement II Hard3519 Count Numbers with Non-Decreasing Digits Hard3522 Calculate Score After Performing Instructions Medium3527 Find the Most Common Response Medium3529 Count Cells in Overlapping Horizontal and Vertical Substrings Medium3541 Find Most Frequent Vowel and Consonant Easy3545 Minimum Deletions for At Most K Distinct Characters Easy3556 Sum of Largest Prime Substrings Medium3557 Find Maximum Number of Non Intersecting Substrings Medium3561 Resulting String After Adjacent Removals Medium3563 Lexicographically Smallest String After Adjacent Removals Hard3579 Minimum Steps to Convert String with Operations Hard3582 Generate Tag for Video Caption Easy3597 Partition String Medium3598 Longest Common Prefix Between Adjacent Strings After Removals Medium3602 Hexadecimal and Hexatrigesimal Conversion Easy3606 Coupon Code Validator Easy3612 Process String with Special Operations I Medium3614 Process String with Special Operations II Hard3615 Longest Palindromic Path in Graph Hard