String Interview Questions

Rank

#3613MediumFrequency: 100%

Maximize Amount After Two Days of Conversions

Array String Depth-First Search Breadth-First Search Graph

Rank

#392EasyFrequency: 100%

Is Subsequence

Rank

#227MediumFrequency: 96%

Basic Calculator II

Math String Stack

Rank

#680EasyFrequency: 95%

Valid Palindrome II

Two Pointers String Greedy

Rank

#415EasyFrequency: 94%

Add Strings

Math String Simulation

Rank

#957MediumFrequency: 94%

Minimum Add to Make Parentheses Valid

String Stack Greedy

Rank

#65HardFrequency: 91%

Valid Number

Rank

#1423MediumFrequency: 91%

Maximum Number of Occurrences of a Substring

Rank

#20EasyFrequency: 90%

Valid Parentheses

#10

Rank

#6MediumFrequency: 88%

Zigzag Conversion

#11

Rank

#408EasyFrequency: 87%

Valid Word Abbreviation

#12

Rank

#394MediumFrequency: 87%

Decode String

String Stack Recursion

#13

Rank

#3MediumFrequency: 84%

Longest Substring Without Repeating Characters

#14

Rank

#387EasyFrequency: 83%

First Unique Character in a String

Hash Table String Queue Counting

#15

Rank

#424MediumFrequency: 82%

Longest Repeating Character Replacement

#16

Rank

#273HardFrequency: 82%

Integer to English Words

Math String Recursion

#17

Rank

#1894EasyFrequency: 80%

Merge Strings Alternately

#18

Rank

#1566EasyFrequency: 80%

Check If a Word Occurs As a Prefix of Any Word in a Sentence

#19

Rank

#151MediumFrequency: 80%

Reverse Words in a String

#20

Rank

#269HardFrequency: 79%

Alien Dictionary

Array String Depth-First Search Breadth-First Search Graph Topological Sort

#21

Rank

#166MediumFrequency: 79%

Fraction to Recurring Decimal

#22

Rank

#125EasyFrequency: 78%

Valid Palindrome

#23

Rank

#2232MediumFrequency: 76%

Adding Spaces to a String

Array Two Pointers String Simulation

#24

Rank

#249MediumFrequency: 76%

Group Shifted Strings

Array Hash Table String

#25

Rank

#14EasyFrequency: 75%

Longest Common Prefix

String Trie

#26

Rank

#1178HardFrequency: 74%

Valid Palindrome III

String Dynamic Programming

#27

Rank

#71MediumFrequency: 73%

Simplify Path

#28

Rank

#49MediumFrequency: 72%

Group Anagrams

Array Hash Table String Sorting

#29

Rank

#778MediumFrequency: 72%

Reorganize String

Hash Table String Greedy Sorting Heap (Priority Queue)Counting

#30

Rank

#58EasyFrequency: 72%

Length of Last Word

Asked at TikTok

#31

Rank

#383EasyFrequency: 72%

Ransom Note

#32

Rank

#2532EasyFrequency: 71%

Remove Letter To Equalize Frequency

#33

Rank

#10HardFrequency: 70%

Regular Expression Matching

String Dynamic Programming Recursion

#34

Rank

#753MediumFrequency: 69%

Open the Lock

Array Hash Table String Breadth-First Search

#35

Rank

#807MediumFrequency: 68%

Custom Sort String

#36

Rank

#5MediumFrequency: 65%

Longest Palindromic Substring

#37

Rank

#127HardFrequency: 64%

Word Ladder

Hash Table String Breadth-First Search

#38

Rank

#2414MediumFrequency: 64%

Move Pieces to Obtain a String

#39

Rank

#79MediumFrequency: 63%

Word Search

Array String Backtracking Matrix

#40

Rank

#399MediumFrequency: 63%

Evaluate Division

Array String Depth-First Search Breadth-First Search Union Find Graph Shortest Path

#41

Rank

#244MediumFrequency: 63%

Shortest Word Distance II

Asked at LinkedIn

Array Hash Table Two Pointers String Design

#42

Rank

#12MediumFrequency: 63%

Integer to Roman

#43

Rank

#721MediumFrequency: 62%

Accounts Merge

Array Hash Table String Depth-First Search Breadth-First Search Union Find Sorting

#44

Rank

#3018MediumFrequency: 60%

Make String a Subsequence Using Cyclic Increments

#45

Rank

#76HardFrequency: 60%

Minimum Window Substring

#46

Rank

#2300MediumFrequency: 59%

Construct String With Repeat Limit

Hash Table String Greedy Heap (Priority Queue)Counting

#47

Rank

#1737EasyFrequency: 59%

Maximum Nesting Depth of the Parentheses

#48

Rank

#139MediumFrequency: 57%

Word Break

Array Hash Table String Dynamic Programming Trie Memoization

#49

Rank

#17MediumFrequency: 56%

Letter Combinations of a Phone Number

#50

Rank

#224HardFrequency: 56%

Basic Calculator

Math String Stack Recursion

#51

Rank

#205EasyFrequency: 55%

Isomorphic Strings

Hash Table String

#52

Rank

#291MediumFrequency: 55%

Word Pattern II

#53

Rank

#567MediumFrequency: 55%

Permutation in String

Hash Table Two Pointers String Sliding Window

#54

Rank

#1128EasyFrequency: 55%

Remove All Adjacent Duplicates In String

#55

Rank

#22MediumFrequency: 53%

Generate Parentheses

String Dynamic Programming Backtracking

#56

Rank

#126HardFrequency: 52%

Word Ladder II

Hash Table String Backtracking Breadth-First Search

#57

Rank

#3410HardFrequency: 51%

Find Longest Self-Contained Substring

Hash Table String Binary Search Prefix Sum

#58

Rank

#28EasyFrequency: 48%

Find the Index of the First Occurrence in a String

#59

Rank

#13EasyFrequency: 44%

Roman to Integer

#60

Rank

#647MediumFrequency: 43%

Palindromic Substrings

#61

Rank

#851EasyFrequency: 43%

Goat Latin

#62

Rank

#2021MediumFrequency: 43%

Remove All Occurrences of a Substring

String Stack Simulation

#63

Rank

#179MediumFrequency: 42%

Largest Number

Array String Greedy Sorting

#64

Rank

#282HardFrequency: 37%

Expression Add Operators

Math String Backtracking

#65

Rank

#752MediumFrequency: 37%

IP to CIDR

String Bit Manipulation

#66

Rank

#1397MediumFrequency: 33%

Search Suggestions System

Array String Binary Search Trie Sorting Heap (Priority Queue)

#67

Rank

#242EasyFrequency: 22%

Valid Anagram

#68

Rank

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String Interview Questions

Master 68 string problems frequently asked in technical interviews. These questions test your understanding of stringconcepts and are essential for coding interview success.

Total Problems

Easy

Medium

Hard

Minimum Remove to Make Valid Parentheses

Rank

#3613MediumFrequency: 100%

Maximize Amount After Two Days of Conversions

Array String Depth-First Search Breadth-First Search Graph

Rank

#392EasyFrequency: 100%

Is Subsequence

Rank

#227MediumFrequency: 96%

Basic Calculator II

Math String Stack

Rank

#680EasyFrequency: 95%

Valid Palindrome II

Two Pointers String Greedy

Rank

#415EasyFrequency: 94%

Add Strings

Math String Simulation

Rank

#957MediumFrequency: 94%

Minimum Add to Make Parentheses Valid

String Stack Greedy

Rank

#65HardFrequency: 91%

Valid Number

Rank

#1423MediumFrequency: 91%

Maximum Number of Occurrences of a Substring

Rank

#20EasyFrequency: 90%

Valid Parentheses

#10

Rank

#6MediumFrequency: 88%

Zigzag Conversion

#11

Rank

#408EasyFrequency: 87%

Valid Word Abbreviation

#12

Rank

#394MediumFrequency: 87%

Decode String

String Stack Recursion

#13

Rank

#3MediumFrequency: 84%

Longest Substring Without Repeating Characters

#14

Rank

#387EasyFrequency: 83%

First Unique Character in a String

Hash Table String Queue Counting

#15

Rank

#424MediumFrequency: 82%

Longest Repeating Character Replacement

#16

Rank

#273HardFrequency: 82%

Integer to English Words

Math String Recursion

#17

Rank

#1894EasyFrequency: 80%

Merge Strings Alternately

#18

Rank

#1566EasyFrequency: 80%

Check If a Word Occurs As a Prefix of Any Word in a Sentence

#19

Rank

#151MediumFrequency: 80%

Reverse Words in a String

#20

Rank

#269HardFrequency: 79%

Alien Dictionary

Array String Depth-First Search Breadth-First Search Graph Topological Sort

#21

Rank

#166MediumFrequency: 79%

Fraction to Recurring Decimal

#22

Rank

#125EasyFrequency: 78%

Valid Palindrome

#23

Rank

#2232MediumFrequency: 76%

Adding Spaces to a String

Array Two Pointers String Simulation

#24

Rank

#249MediumFrequency: 76%

Group Shifted Strings

Array Hash Table String

#25

Rank

#14EasyFrequency: 75%

Longest Common Prefix

String Trie

#26

Rank

#1178HardFrequency: 74%

Valid Palindrome III

String Dynamic Programming

#27

Rank

#71MediumFrequency: 73%

Simplify Path

#28

Rank

#49MediumFrequency: 72%

Group Anagrams

Array Hash Table String Sorting

#29

Rank

#778MediumFrequency: 72%

Reorganize String

Hash Table String Greedy Sorting Heap (Priority Queue)Counting

#30

Rank

#58EasyFrequency: 72%

Length of Last Word

Asked at TikTok

#31

Rank

#383EasyFrequency: 72%

Ransom Note

#32

Rank

#2532EasyFrequency: 71%

Remove Letter To Equalize Frequency

#33

Rank

#10HardFrequency: 70%

Regular Expression Matching

String Dynamic Programming Recursion

#34

Rank

#753MediumFrequency: 69%

Open the Lock

Array Hash Table String Breadth-First Search

#35

Rank

#807MediumFrequency: 68%

Custom Sort String

#36

Rank

#5MediumFrequency: 65%

Longest Palindromic Substring

#37

Rank

#127HardFrequency: 64%

Word Ladder

Hash Table String Breadth-First Search

#38

Rank

#2414MediumFrequency: 64%

Move Pieces to Obtain a String

#39

Rank

#79MediumFrequency: 63%

Word Search

Array String Backtracking Matrix

#40

Rank

#399MediumFrequency: 63%

Evaluate Division

Array String Depth-First Search Breadth-First Search Union Find Graph Shortest Path

#41

Rank

#244MediumFrequency: 63%

Shortest Word Distance II

Asked at LinkedIn

Array Hash Table Two Pointers String Design

#42

Rank

#12MediumFrequency: 63%

Integer to Roman

#43

Rank

#721MediumFrequency: 62%

Accounts Merge

Array Hash Table String Depth-First Search Breadth-First Search Union Find Sorting

#44

Rank

#3018MediumFrequency: 60%

Make String a Subsequence Using Cyclic Increments

#45

Rank

#76HardFrequency: 60%

Minimum Window Substring

#46

Rank

#2300MediumFrequency: 59%

Construct String With Repeat Limit

Hash Table String Greedy Heap (Priority Queue)Counting

#47

Rank

#1737EasyFrequency: 59%

Maximum Nesting Depth of the Parentheses

#48

Rank

#139MediumFrequency: 57%

Word Break

Array Hash Table String Dynamic Programming Trie Memoization

#49

Rank

#17MediumFrequency: 56%

Letter Combinations of a Phone Number

#50

Rank

#224HardFrequency: 56%

Basic Calculator

Math String Stack Recursion

#51

Rank

#205EasyFrequency: 55%

Isomorphic Strings

Hash Table String

#52

Rank

#291MediumFrequency: 55%

Word Pattern II

#53

Rank

#567MediumFrequency: 55%

Permutation in String

Hash Table Two Pointers String Sliding Window

#54

Rank

#1128EasyFrequency: 55%

Remove All Adjacent Duplicates In String

#55

Rank

#22MediumFrequency: 53%

Generate Parentheses

String Dynamic Programming Backtracking

#56

Rank

#126HardFrequency: 52%

Word Ladder II

Hash Table String Backtracking Breadth-First Search

#57

Rank

#3410HardFrequency: 51%

Find Longest Self-Contained Substring

Hash Table String Binary Search Prefix Sum

#58

Rank

#28EasyFrequency: 48%

Find the Index of the First Occurrence in a String

#59

Rank

#13EasyFrequency: 44%

Roman to Integer

#60

Rank

#647MediumFrequency: 43%

Palindromic Substrings

#61

Rank

#851EasyFrequency: 43%

Goat Latin

#62

Rank

#2021MediumFrequency: 43%

Remove All Occurrences of a Substring

String Stack Simulation

#63

Rank

#179MediumFrequency: 42%

Largest Number

Array String Greedy Sorting

#64

Rank

#282HardFrequency: 37%

Expression Add Operators

Math String Backtracking

#65

Rank

#752MediumFrequency: 37%

IP to CIDR

String Bit Manipulation

#66

Rank

#1397MediumFrequency: 33%

Search Suggestions System

Array String Binary Search Trie Sorting Heap (Priority Queue)

#67

Rank

#242EasyFrequency: 22%

Valid Anagram