Google String Questions

539 string problems asked at Google interviews

Easy (157)Medium (262)Hard (120)

Questions

TitleDifficulty
Longest Common PrefixEasy
Longest Substring Without Repeating CharactersMedium
Merge Strings AlternatelyEasy
Longest Palindromic SubstringMedium
Valid ParenthesesEasy
Roman to IntegerEasy
Generate ParenthesesMedium
Decode StringMedium
Letter Combinations of a Phone NumberMedium
Valid AnagramEasy
Find the Index of the First Occurrence in a StringEasy
Group AnagramsMedium
Longest Repeating Character ReplacementMedium
Add BinaryEasy
Zigzag ConversionMedium
Regular Expression MatchingHard
Valid PalindromeEasy
Basic CalculatorHard
Reverse Words in a StringMedium
Guess the WordHard
Edit DistanceMedium
Remove K DigitsMedium
Length of Last WordEasy
Reverse Vowels of a StringEasy
Isomorphic StringsEasy
Text JustificationHard
Word BreakMedium
Palindrome PartitioningMedium
Wildcard MatchingHard
Reverse StringEasy
Largest NumberMedium
String to Integer (atoi)Medium
String CompressionMedium
Word SearchMedium
Minimum Window SubstringHard
Move Pieces to Obtain a StringMedium
Permutation in StringMedium
Integer to RomanMedium
Apply SubstitutionsMedium
First Unique Character in a StringEasy
Greatest Common Divisor of StringsEasy
Find the DifferenceEasy
Word LadderHard
Swap Adjacent in LR StringMedium
Is SubsequenceEasy
Add StringsEasy
Longest Valid ParenthesesHard
Ransom NoteEasy
Fizz BuzzEasy
Rotate StringEasy
Longest Common SubsequenceMedium
Serialize and Deserialize Binary TreeHard
Shortest PalindromeHard
Reorganize StringMedium
Group Shifted StringsMedium
Evaluate DivisionMedium
Expression Add OperatorsHard
Implement Trie (Prefix Tree)Medium
Valid Palindrome IIEasy
Find All Possible Recipes from Given SuppliesMedium
Lexicographically Smallest Beautiful StringHard
Simplify PathMedium
Alien DictionaryHard
Number of Matching SubsequencesMedium
Word Search IIHard
Multiply StringsMedium
Find And Replace in StringMedium
Repeated Substring PatternEasy
Accounts MergeMedium
Minimum Number of Operations to Move All Balls to Each BoxMedium
Substring with Concatenation of All WordsHard
Backspace String CompareEasy
Reverse String IIEasy
Remove Duplicate LettersMedium
Integer to English WordsHard
Find Longest Special Substring That Occurs Thrice IMedium
Remove Outermost ParenthesesEasy
Score of a StringEasy
Sort Characters By FrequencyMedium
Binary Tree PathsEasy
Fraction to Recurring DecimalMedium
Count and SayMedium
Find All Anagrams in a StringMedium
Unique Length-3 Palindromic SubsequencesMedium
Reconstruct ItineraryHard
Encode and Decode StringsMedium
Excel Sheet Column TitleEasy
Longest PalindromeEasy
Top K Frequent WordsMedium
Palindromic SubstringsMedium
Remove Sub-Folders from the FilesystemMedium
Word Break IIHard
Maximum Score After Splitting a StringEasy
Repeated String MatchMedium
Decode WaysMedium
Jewels and StonesEasy
Longest Absolute File PathMedium
Sender With Largest Word CountMedium
Valid Parenthesis StringMedium
Minimum Add to Make Parentheses ValidMedium
Sum of Beauty of All SubstringsMedium
Minimum Time DifferenceMedium
Maximum Score From Removing SubstringsMedium
Detect CapitalEasy
Design a Text EditorHard
Word Ladder IIHard
Robot Return to OriginEasy
Basic Calculator IIMedium
Longest Duplicate SubstringHard
Make The String GreatEasy
Time Based Key-Value StoreMedium
Longest Palindromic SubsequenceMedium
First Letter to Appear TwiceEasy
Palindrome PairsHard
Word SubsetsMedium
Valid Word AbbreviationEasy
Expressive WordsMedium
Rank Teams by VotesMedium
Interleaving StringMedium
Minimum Number of Flips to Make the Binary String AlternatingMedium
Shortest Common SupersequenceHard
Counting Words With a Given PrefixEasy
Maximum Product of Word LengthsMedium
Ones and ZeroesMedium
Delete Operation for Two StringsMedium
Find the Length of the Longest Common PrefixMedium
Words Within Two Edits of DictionaryMedium
Design Search Autocomplete SystemHard
Number of Substrings Containing All Three CharactersMedium
Minimum Deletions to Make String BalancedMedium
Pyramid Transition MatrixMedium
Distinct SubsequencesHard
Buddy StringsEasy
Unique Email AddressesEasy
Evaluate the Bracket Pairs of a StringMedium
Remove All Adjacent Duplicates In StringEasy
Check If a String Contains All Binary Codes of Size KMedium
Defanging an IP AddressEasy
Number of Unique Good SubsequencesHard
Push DominoesMedium
Delete Columns to Make Sorted IIMedium
Bulls and CowsMedium
Smallest String Starting From LeafMedium
Flip String to Monotone IncreasingMedium
Delete Columns to Make SortedEasy
Minimum Distance to Type a Word Using Two FingersHard
Longest String ChainMedium
Minimum Remove to Make Valid ParenthesesMedium
Design Add and Search Words Data StructureMedium
Next Closest TimeMedium
Number of Good Ways to Split a StringMedium
Cracking the SafeHard
Split a String Into the Max Number of Unique SubstringsMedium
Student Attendance Record IEasy
Longest Word in Dictionary through DeletingMedium
Similar String GroupsHard
Stream of CharactersHard
Number of AtomsHard
Implement Magic DictionaryMedium
Jump Game VIIMedium
The k-th Lexicographical String of All Happy Strings of Length nMedium
Word PatternEasy
Search Suggestions SystemMedium
Remove All Occurrences of a SubstringMedium
Clear DigitsEasy
Number of Same-End SubstringsMedium
License Key FormattingEasy
Maximum Number of Words Found in SentencesEasy
Sentence Similarity IIIMedium
Verify Preorder Serialization of a Binary TreeMedium
Magical StringMedium
Encode and Decode TinyURLMedium
Sentence Similarity IIMedium
Letter Tile PossibilitiesMedium
Latest Time by Replacing Hidden DigitsEasy
Check if DFS Strings Are PalindromesHard
Sentence Screen FittingMedium
DI String MatchEasy
Rearrange String k Distance ApartHard
Palindrome Partitioning IIHard
Number of Wonderful SubstringsMedium
Repeated DNA SequencesMedium
Restore IP AddressesMedium
Longest Palindromic Subsequence After at Most K OperationsMedium
Largest Odd Number in StringEasy
Design Compressed String IteratorEasy
Largest Color Value in a Directed GraphHard
Freedom TrailHard
Longest Uncommon Subsequence IIMedium
Determine if Two Events Have ConflictEasy
Longest Substring with At Most Two Distinct CharactersMedium
Check if Number Has Equal Digit Count and Digit ValueEasy
Longest Binary Subsequence Less Than or Equal to KMedium
Sum of Prefix Scores of StringsHard
Minimum Window SubsequenceHard
Sentence SimilarityEasy
K-Similar StringsHard
String TransformationHard
Delete Columns to Make Sorted IIIHard
Single-Row KeyboardEasy
Smallest Subsequence of Distinct CharactersMedium
Alphabet Board PathMedium
Reverse Only LettersEasy
Binary String With Substrings Representing 1 To NMedium
Longest Common Suffix QueriesHard
Final Value of Variable After Performing OperationsEasy
Longest Substring with At Least K Repeating CharactersMedium
Basic Calculator IIIHard
Parsing A Boolean ExpressionHard
Partition StringMedium
Strobogrammatic Number IIMedium
Longest Substring with At Most K Distinct CharactersMedium
Rearrange Spaces Between WordsEasy
Number of Valid Clock TimesEasy
Count K-Subsequences of a String With Maximum BeautyHard
Find Longest Special Substring That Occurs Thrice IIMedium
Split Two Strings to Make PalindromeMedium
Longest Happy PrefixHard
Replace All Digits with CharactersEasy
Minimum Time to Remove All Cars Containing Illegal GoodsHard
Strobogrammatic NumberEasy
Count Prefixes of a Given StringEasy
Count AsterisksEasy
Number of Beautiful PartitionsHard
Word AbbreviationHard
Output Contest MatchesMedium
Make Number of Distinct Characters EqualMedium
Add Bold Tag in StringMedium
Shortest Completing WordEasy
Super PalindromesHard
Brace Expansion IIHard
Minimum Number of Operations to Make Word K-PeriodicMedium
Simplified FractionsMedium
Longest Chunked Palindrome DecompositionHard
Distinct Echo SubstringsHard
Shuffle StringEasy
Scramble StringHard
Number of Ways to Form a Target String Given a DictionaryHard
Different Ways to Add ParenthesesMedium
Count the Number of Substrings With Dominant OnesMedium
Find Beautiful Indices in the Given Array IIHard
Shifting Letters IIMedium
Count Cells in Overlapping Horizontal and Vertical SubstringsMedium
Maximum Number of Operations to Move Ones to the EndMedium
Brace ExpansionMedium
Flip GameEasy
Rings and RodsEasy
Minimum Number of Operations to Convert TimeEasy
Count Words Obtained After Adding a LetterMedium
Minimum White Tiles After Covering With CarpetsHard
Palindrome PermutationEasy
Unique Word AbbreviationMedium
Generalized AbbreviationMedium
Minimum Unique Word AbbreviationHard
Word SquaresHard
Encode String with Shortest LengthHard
Find PermutationMedium
Longest Uncommon Subsequence IEasy
Bold Words in StringMedium
Similar RGB ColorEasy
Ambiguous CoordinatesMedium
Positions of Large GroupsEasy
Shortest Way to Form StringMedium
Camelcase MatchingMedium
String Transforms Into Another StringHard
Occurrences After BigramEasy
Iterator for CombinationMedium
Compare Strings by Frequency of the Smallest CharacterMedium
Latest Time You Can Obtain After Replacing CharactersEasy
Maximum Font to Fit a Sentence in a ScreenMedium
People Whose List of Favorite Companies Is Not a Subset of Another ListMedium
Number of Substrings With Only 1sMedium
The Most Similar Path in a GraphHard
Check If String Is Transformable With Substring Sort OperationsHard
Change Minimum Characters to Satisfy One of Three ConditionsMedium
Count Pairs of Equal Substrings With Minimum DifferenceMedium
Minimum Adjacent Swaps to Reach the Kth Smallest NumberMedium
Minimum Cost to Change the Final Value of ExpressionHard
Longest Word With All PrefixesMedium
Count Caesar Cipher PairsMedium
Minimum Genetic MutationMedium
Special Binary StringHard
Subdomain Visit CountMedium
Check if the Sentence Is PangramEasy
Determine if Two Strings Are CloseMedium
Find Common CharactersEasy
Recover a Tree From Preorder TraversalHard
Minimum Number of Swaps to Make the String BalancedMedium
Find the Original Typed String IIHard
Serialize and Deserialize N-ary TreeHard
Find Unique Binary StringMedium
Keyboard RowEasy
Find the Shortest SuperstringHard
Excel Sheet Column NumberEasy
Valid NumberHard
Count Binary SubstringsEasy
Next Greater Element IIIMedium
String Compression IIIMedium
Additive NumberMedium
String Matching in an ArrayEasy
Largest 3-Same-Digit Number in StringEasy
Reverse Words in a String IIIEasy
Check if a Parentheses String Can Be ValidMedium
Step-By-Step Directions From a Binary Tree Node to AnotherMedium
Long Pressed NameEasy
Partition LabelsMedium
Longest Happy StringMedium
Find Kth Bit in Nth Binary StringMedium
Sorting the SentenceEasy
Base 7Easy
Extra Characters in a StringMedium
Maximum Nesting Depth of the ParenthesesEasy
Find Words Containing CharacterEasy
Remove Invalid ParenthesesHard
To Lower CaseEasy
Delete Characters to Make Fancy StringEasy
Count Number of Balanced PermutationsHard
Smallest String With SwapsMedium
Find the Lexicographically Largest String From the Box IMedium
Count the Number of Powerful IntegersHard
Convert a Number to HexadecimalEasy
Dota2 SenateMedium
Shortest Distance to a CharacterEasy
Minimum Cost to Convert String IMedium
Number of Steps to Reduce a Number in Binary Representation to OneMedium
Count Vowel Substrings of a StringEasy
Day of the YearEasy
Remove All Adjacent Duplicates in String IIMedium
Longest Palindrome by Concatenating Two Letter WordsMedium
Open the LockMedium
Fraction Addition and SubtractionMedium
Removing Stars From a StringMedium
Generate Binary Strings Without Adjacent ZerosMedium
Construct K Palindrome StringsMedium
Adding Spaces to a StringMedium
Take K of Each Character From Left and RightMedium
Construct String With Repeat LimitMedium
Design Excel Sum FormulaHard
Minimum Recolors to Get K Consecutive Black BlocksEasy
Longest Subsequence Repeated k TimesHard
Find the Original Typed String IEasy
Compare Version NumbersMedium
Minimum Number of Steps to Make Two Strings AnagramMedium
Reverse Prefix of WordEasy
Find Resultant Array After Removing AnagramsEasy
Count the Number of Special Characters IIMedium
Longest Balanced Substring IIMedium
Invalid TransactionsMedium
Remove Letter To Equalize FrequencyEasy
Find Most Frequent Vowel and ConsonantEasy
Find the Closest PalindromeHard
Most Common WordEasy
Number of Senior CitizensEasy
Count the Number of Consistent StringsEasy
Find the Longest Substring Containing Vowels in Even CountsMedium
Minimum Number of Changes to Make Binary String BeautifulMedium
Total Characters in String After Transformations IIHard
Sort the PeopleEasy
Minimum String Length After Removing SubstringsEasy
Minimum Swaps to Make Strings EqualMedium
Reconstruct Original Digits from EnglishMedium
Minimum Insertion Steps to Make a String PalindromeHard
Lexicographically Minimum String After Removing StarsMedium
Maximum Difference Between Even and Odd Frequency IIHard
Find the Occurrence of First Almost Equal SubstringHard
Valid WordEasy
Maximum Number of Words You Can TypeEasy
Distinct Subsequences IIHard
Maximize the Confusion of an ExamMedium
Design In-Memory File SystemHard
Design File SystemMedium
Sort Vowels in a StringMedium
Uncommon Words from Two SentencesEasy
Minimum Penalty for a ShopMedium
Custom Sort StringMedium
Minimum ASCII Delete Sum for Two StringsMedium
Process String with Special Operations IIHard
Find Words That Can Be Formed by CharactersEasy
Lexicographically Smallest Generated StringHard
Concatenate Non-Zero Digits and Multiply by Sum IIMedium
Verifying an Alien DictionaryEasy
Score of ParenthesesMedium
Validate IP AddressMedium
Number of Lines To Write StringEasy
Find and Replace PatternMedium
Number of Days Between Two DatesEasy
Maximum Number of Vowels in a Substring of Given LengthMedium
Path CrossingEasy
Remove Digit From Number to Maximize ResultEasy
Satisfiability of Equality EquationsMedium
Design a Food Rating SystemMedium
Maximum Odd Binary NumberEasy
Basic Calculator IVHard
Tweet Counts Per FrequencyMedium
Separate Black and White BallsMedium
Maximum Repeating SubstringEasy
Serialize and Deserialize BSTMedium
Delete Duplicate Folders in SystemHard
Lexicographically Smallest Equivalent StringMedium
Number of Segments in a StringEasy
Analyze User Website Visit PatternMedium
Check if One String Swap Can Make Strings EqualEasy
Check If Digits Are Equal in String After Operations IEasy
Maximum Nesting Depth of Two Valid Parentheses StringsMedium
Vowel SpellcheckerMedium
Strange PrinterHard
Longest Nice SubstringEasy
Count the Number of Special Characters IEasy
Find the String with LCPHard
Parse Lisp ExpressionHard
String Without AAA or BBBMedium
Decode the MessageEasy
Minimum Operations to Equalize Binary StringHard
Design SpreadsheetMedium
Check if Strings Can be Made Equal With Operations IEasy
Check if Strings Can be Made Equal With Operations IIMedium
Partitioning Into Minimum Number Of Deci-Binary NumbersMedium
Minimum Number of Pushes to Type Word IEasy
Decode the Slanted CiphertextMedium
Furthest Point From OriginEasy
Check If Two String Arrays are EquivalentEasy
Count Number of Homogenous SubstringsMedium
Minimum Additions to Make Valid StringMedium
Check If a Word Occurs As a Prefix of Any Word in a SentenceEasy
Maximum Score Words Formed by LettersHard
Count Palindromic SubsequencesHard
Minimum Moves to Convert StringEasy
Sum of Digits of String After ConvertEasy
Remove CommentsMedium
Shortest String That Contains Three StringsMedium
Unique Substrings in Wraparound StringMedium
Split Array into Fibonacci SequenceMedium
Swap For Longest Repeated Character SubstringMedium
Count Items Matching a RuleEasy
Hash Divided StringMedium
Total Appeal of A StringHard
Construct Smallest Number From DI StringMedium
Find the Divisibility Array of a StringMedium
Shifting LettersMedium
Divide a String Into Groups of Size kEasy
Total Characters in String After Transformations IMedium
Generate a String With Characters That Have Odd CountsEasy
Maximum Product of the Length of Two Palindromic SubsequencesMedium
Design Underground SystemMedium
Count Collisions on a RoadMedium
Maximum Difference Between Even and Odd Frequency IEasy
Vowels Game in a StringMedium
Shortest Word Distance IIMedium
Coupon Code ValidatorEasy
Find Beautiful Indices in the Given Array IMedium
Verbal Arithmetic PuzzleHard
HTML Entity ParserMedium
Append Characters to String to Make SubsequenceMedium
Letter Case PermutationMedium
Strong Password CheckerHard
Count The RepetitionsHard
Two-Letter Card GameMedium
Maximum Number of BalloonsEasy
Traffic Signal ColorEasy
Count Residue PrefixesEasy
Longest Balanced Substring IMedium
Check if Binary String Has at Most One Segment of OnesEasy
Weighted Word MappingEasy
Stickers to Spell WordHard
Optimal Partition of StringMedium
Prefix and Suffix SearchHard
Replace WordsMedium
Reverse Substrings Between Each Pair of ParenthesesMedium
Kth Distinct String in an ArrayEasy
Find the Largest Palindrome Divisible by KHard
Goal Parser InterpretationEasy
Check if All Characters Have Equal Number of OccurrencesEasy
Find All Good StringsHard
Snake in MatrixEasy
Count Substrings With K-Frequency Characters IMedium
Convert Date to BinaryEasy
Count Prefix and Suffix Pairs IEasy
Count Substrings That Satisfy K-Constraint IEasy
Determine if String Halves Are AlikeEasy
Find Maximum Removals From Source StringMedium
Minimum Operations to Make Character Frequencies EqualHard
Maximize Amount After Two Days of ConversionsMedium
Find the Kth Largest Integer in the ArrayMedium
Split a String in Balanced StringsEasy
Map Sum PairsMedium
Minimum Index Sum of Two ListsEasy
Minimum Insertions to Balance a Parentheses StringMedium
Encrypt and Decrypt StringsHard
Count Vowel Strings in RangesMedium
Length of the Longest Valid SubstringHard
String Compression IIHard
Longest Repeating SubstringMedium
Minimum Deletions to Make String K-SpecialMedium
Equal Rational NumbersHard
Reorder Data in Log FilesMedium
Longest Word in DictionaryMedium
Shift Distance Between Two StringsMedium
Maximum Length of a Concatenated String with Unique CharactersMedium
The Maze IIIHard
Count Different Palindromic SubsequencesHard
Maximum Value of a String in an ArrayEasy
Longest Palindrome After Substring Concatenation IMedium
Increasing Decreasing StringEasy
Minimum Cost to Convert String IIHard
Check If Digits Are Equal in String After Operations IIHard
Minimum Deletions to Make Character Frequencies UniqueMedium
Solve the EquationMedium
Find Substring With Given Hash ValueHard
Robot Bounded In CircleMedium
Find Mirror Score of a StringMedium
Count The Number of Winning SequencesHard
Minimize String LengthEasy
Longest Palindrome After Substring Concatenation IIHard
Count Substrings Divisible By Last DigitHard
Lexicographically Smallest Permutation Greater Than TargetMedium
Number of Valid Move Combinations On ChessboardHard
Decrypt String from Alphabet to Integer MappingEasy
One Edit DistanceMedium
Second Largest Digit in a StringEasy
Zuma GameHard
Masking Personal InformationMedium
Find Duplicate File in SystemMedium
Restore The ArrayHard
Maximize Active Section with Trade IMedium
IP to CIDRMedium
Find Valid Pair of Adjacent Digits in StringEasy
Minimum Deletions for At Most K Distinct CharactersEasy
Smallest Divisible Digit Product IIHard
Reverse Degree of a StringEasy
Find the K-Beauty of a NumberEasy
Minimum Amount of Time to Collect GarbageMedium
Numbers At Most N Given Digit SetHard
Longest Balanced Substring After One SwapMedium
Count Stepping Numbers in RangeHard
Longest Palindromic Path in GraphHard
Plates Between CandlesMedium
Process String with Special Operations IMedium
Longest Substring Of All Vowels in OrderMedium
Maximum Number of Occurrences of a SubstringMedium

Showing 539 questions