String Interview Questions

Rank

#3638HardFrequency: 100%

Minimum Operations to Make Character Frequencies Equal

Hash Table String Dynamic Programming Counting Enumeration

Rank

#3613MediumFrequency: 100%

Maximize Amount After Two Days of Conversions

Array String Depth-First Search Breadth-First Search Graph

Rank

#49MediumFrequency: 100%

Group Anagrams

Array Hash Table String Sorting

Rank

#71MediumFrequency: 100%

Simplify Path

Rank

#1423MediumFrequency: 100%

Maximum Number of Occurrences of a Substring

Rank

#227MediumFrequency: 96%

Basic Calculator II

Math String Stack

Rank

#680EasyFrequency: 95%

Valid Palindrome II

Two Pointers String Greedy

Rank

#647MediumFrequency: 88%

Palindromic Substrings

Rank

#408EasyFrequency: 87%

Valid Word Abbreviation

#10

Rank

#125EasyFrequency: 87%

Valid Palindrome

#11

Rank

#3MediumFrequency: 84%

Longest Substring Without Repeating Characters

#12

Rank

#8MediumFrequency: 84%

String to Integer (atoi)

#13

Rank

#752MediumFrequency: 84%

IP to CIDR

String Bit Manipulation

#14

Rank

#1894EasyFrequency: 80%

Merge Strings Alternately

#15

Rank

#14EasyFrequency: 80%

Longest Common Prefix

String Trie

#16

Rank

#269HardFrequency: 79%

Alien Dictionary

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

#17

Rank

#224HardFrequency: 73%

Basic Calculator

Math String Stack Recursion

#18

Rank

#1397MediumFrequency: 73%

Search Suggestions System

Array String Binary Search Trie Sorting Heap (Priority Queue)

#19

Rank

#1915EasyFrequency: 73%

Check if One String Swap Can Make Strings Equal

#20

Rank

#778MediumFrequency: 72%

Reorganize String

Hash Table String Greedy Sorting Heap (Priority Queue)Counting

#21

Rank

#139MediumFrequency: 72%

Word Break

Array Hash Table String Dynamic Programming Trie Memoization

#22

Rank

#20EasyFrequency: 71%

Valid Parentheses

#23

Rank

#127HardFrequency: 71%

Word Ladder

Hash Table String Breadth-First Search

#24

Rank

#65HardFrequency: 69%

Valid Number

#25

Rank

#957MediumFrequency: 66%

Minimum Add to Make Parentheses Valid

String Stack Greedy

#26

Rank

#79MediumFrequency: 63%

Word Search

Array String Backtracking Matrix

#27

Rank

#399MediumFrequency: 63%

Evaluate Division

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

#28

Rank

#244MediumFrequency: 63%

Shortest Word Distance II

Asked at LinkedIn

Array Hash Table Two Pointers String Design

#29

Rank

#721MediumFrequency: 62%

Accounts Merge

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

#30

Rank

#1178HardFrequency: 62%

Valid Palindrome III

String Dynamic Programming

#31

Rank

#415EasyFrequency: 62%

Add Strings

Math String Simulation

#32

Rank

#2414MediumFrequency: 60%

Move Pieces to Obtain a String

#33

Rank

#3018MediumFrequency: 60%

Make String a Subsequence Using Cyclic Increments

#34

Rank

#76HardFrequency: 60%

Minimum Window Substring

#35

Rank

#807MediumFrequency: 60%

Custom Sort String

Hash Table String Sorting

#36

Rank

#6MediumFrequency: 56%

Zigzag Conversion

#37

Rank

#17MediumFrequency: 56%

Letter Combinations of a Phone Number

#38

Rank

#5MediumFrequency: 55%

Longest Palindromic Substring

#39

Rank

#12MediumFrequency: 55%

Integer to Roman

#40

Rank

#205EasyFrequency: 55%

Isomorphic Strings

Hash Table String

#41

Rank

#273HardFrequency: 55%

Integer to English Words

Math String Recursion

#42

Rank

#291MediumFrequency: 55%

Word Pattern II

#43

Rank

#567MediumFrequency: 55%

Permutation in String

Hash Table Two Pointers String Sliding Window

#44

Rank

#1128EasyFrequency: 55%

Remove All Adjacent Duplicates In String

#45

Rank

#1566EasyFrequency: 55%

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

#46

Rank

#22MediumFrequency: 53%

Generate Parentheses

String Dynamic Programming Backtracking

#47

Rank

#2300MediumFrequency: 53%

Construct String With Repeat Limit

Hash Table String Greedy Heap (Priority Queue)Counting

#48

Rank

#387EasyFrequency: 51%

First Unique Character in a String

Hash Table String Queue Counting

#49

Rank

#28EasyFrequency: 48%

Find the Index of the First Occurrence in a String

#50

Rank

#2232MediumFrequency: 48%

Adding Spaces to a String

Array Two Pointers String Simulation

#51

Rank

#10HardFrequency: 45%

Regular Expression Matching

String Dynamic Programming Recursion

#52

Rank

#126HardFrequency: 45%

Word Ladder II

Hash Table String Backtracking Breadth-First Search

#53

Rank

#151MediumFrequency: 45%

Reverse Words in a String

#54

Rank

#3410HardFrequency: 45%

Find Longest Self-Contained Substring

Hash Table String Binary Search Prefix Sum

#55

Rank

#249MediumFrequency: 43%

Group Shifted Strings

Array Hash Table String

#56

Rank

#851EasyFrequency: 43%

Goat Latin

#57

Rank

#13EasyFrequency: 42%

Roman to Integer

#58

Rank

#179MediumFrequency: 42%

Largest Number

Array String Greedy Sorting

#59

Rank

#383EasyFrequency: 42%

Ransom Note

#60

Rank

#394MediumFrequency: 42%

Decode String

String Stack Recursion

#61

Rank

#424MediumFrequency: 42%

Longest Repeating Character Replacement

#62

Rank

#282HardFrequency: 37%

Expression Add Operators

Math String Backtracking

#63

Rank

#58EasyFrequency: 33%

Length of Last Word

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#64

Rank

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String Interview Questions

Master 64 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

#3638HardFrequency: 100%

Minimum Operations to Make Character Frequencies Equal

Hash Table String Dynamic Programming Counting Enumeration

Rank

#3613MediumFrequency: 100%

Maximize Amount After Two Days of Conversions

Array String Depth-First Search Breadth-First Search Graph

Rank

#49MediumFrequency: 100%

Group Anagrams

Array Hash Table String Sorting

Rank

#71MediumFrequency: 100%

Simplify Path

Rank

#1423MediumFrequency: 100%

Maximum Number of Occurrences of a Substring

Rank

#227MediumFrequency: 96%

Basic Calculator II

Math String Stack

Rank

#680EasyFrequency: 95%

Valid Palindrome II

Two Pointers String Greedy

Rank

#647MediumFrequency: 88%

Palindromic Substrings

Rank

#408EasyFrequency: 87%

Valid Word Abbreviation

#10

Rank

#125EasyFrequency: 87%

Valid Palindrome

#11

Rank

#3MediumFrequency: 84%

Longest Substring Without Repeating Characters

#12

Rank

#8MediumFrequency: 84%

String to Integer (atoi)

#13

Rank

#752MediumFrequency: 84%

IP to CIDR

String Bit Manipulation

#14

Rank

#1894EasyFrequency: 80%

Merge Strings Alternately

#15

Rank

#14EasyFrequency: 80%

Longest Common Prefix

String Trie

#16

Rank

#269HardFrequency: 79%

Alien Dictionary

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

#17

Rank

#224HardFrequency: 73%

Basic Calculator

Math String Stack Recursion

#18

Rank

#1397MediumFrequency: 73%

Search Suggestions System

Array String Binary Search Trie Sorting Heap (Priority Queue)

#19

Rank

#1915EasyFrequency: 73%

Check if One String Swap Can Make Strings Equal

#20

Rank

#778MediumFrequency: 72%

Reorganize String

Hash Table String Greedy Sorting Heap (Priority Queue)Counting

#21

Rank

#139MediumFrequency: 72%

Word Break

Array Hash Table String Dynamic Programming Trie Memoization

#22

Rank

#20EasyFrequency: 71%

Valid Parentheses

#23

Rank

#127HardFrequency: 71%

Word Ladder

Hash Table String Breadth-First Search

#24

Rank

#65HardFrequency: 69%

Valid Number

#25

Rank

#957MediumFrequency: 66%

Minimum Add to Make Parentheses Valid

String Stack Greedy

#26

Rank

#79MediumFrequency: 63%

Word Search

Array String Backtracking Matrix

#27

Rank

#399MediumFrequency: 63%

Evaluate Division

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

#28

Rank

#244MediumFrequency: 63%

Shortest Word Distance II

Asked at LinkedIn

Array Hash Table Two Pointers String Design

#29

Rank

#721MediumFrequency: 62%

Accounts Merge

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

#30

Rank

#1178HardFrequency: 62%

Valid Palindrome III

String Dynamic Programming

#31

Rank

#415EasyFrequency: 62%

Add Strings

Math String Simulation

#32

Rank

#2414MediumFrequency: 60%

Move Pieces to Obtain a String

#33

Rank

#3018MediumFrequency: 60%

Make String a Subsequence Using Cyclic Increments

#34

Rank

#76HardFrequency: 60%

Minimum Window Substring

#35

Rank

#807MediumFrequency: 60%

Custom Sort String

Hash Table String Sorting

#36

Rank

#6MediumFrequency: 56%

Zigzag Conversion

#37

Rank

#17MediumFrequency: 56%

Letter Combinations of a Phone Number

#38

Rank

#5MediumFrequency: 55%

Longest Palindromic Substring

#39

Rank

#12MediumFrequency: 55%

Integer to Roman

#40

Rank

#205EasyFrequency: 55%

Isomorphic Strings

Hash Table String

#41

Rank

#273HardFrequency: 55%

Integer to English Words

Math String Recursion

#42

Rank

#291MediumFrequency: 55%

Word Pattern II

#43

Rank

#567MediumFrequency: 55%

Permutation in String

Hash Table Two Pointers String Sliding Window

#44

Rank

#1128EasyFrequency: 55%

Remove All Adjacent Duplicates In String

#45

Rank

#1566EasyFrequency: 55%

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

#46

Rank

#22MediumFrequency: 53%

Generate Parentheses

String Dynamic Programming Backtracking

#47

Rank

#2300MediumFrequency: 53%

Construct String With Repeat Limit

Hash Table String Greedy Heap (Priority Queue)Counting

#48

Rank

#387EasyFrequency: 51%

First Unique Character in a String

Hash Table String Queue Counting

#49

Rank

#28EasyFrequency: 48%

Find the Index of the First Occurrence in a String

#50

Rank

#2232MediumFrequency: 48%

Adding Spaces to a String

Array Two Pointers String Simulation

#51

Rank

#10HardFrequency: 45%

Regular Expression Matching

String Dynamic Programming Recursion

#52

Rank

#126HardFrequency: 45%

Word Ladder II

Hash Table String Backtracking Breadth-First Search

#53

Rank

#151MediumFrequency: 45%

Reverse Words in a String

#54

Rank

#3410HardFrequency: 45%

Find Longest Self-Contained Substring

Hash Table String Binary Search Prefix Sum

#55

Rank

#249MediumFrequency: 43%

Group Shifted Strings

Array Hash Table String

#56

Rank

#851EasyFrequency: 43%

Goat Latin

#57

Rank

#13EasyFrequency: 42%

Roman to Integer

#58

Rank

#179MediumFrequency: 42%

Largest Number

Array String Greedy Sorting

#59

Rank

#383EasyFrequency: 42%

Ransom Note

#60

Rank

#394MediumFrequency: 42%

Decode String

String Stack Recursion

#61

Rank

#424MediumFrequency: 42%

Longest Repeating Character Replacement

#62

Rank

#282HardFrequency: 37%

Expression Add Operators

Math String Backtracking

#63

Rank

#58EasyFrequency: 33%

Length of Last Word