Enumeration Interview Questions

Rank

#3690HardFrequency: 71.5%

Smallest Substring With Identical Characters I

Array Binary Search Enumeration

Rank

#2337EasyFrequency: 59.4%

Remove Digit From Number to Maximize Result

Asked at Infosys

Rank

#3638HardFrequency: 59.3%

Minimum Operations to Make Character Frequencies Equal

Hash Table String Dynamic Programming Counting Enumeration

Rank

#3594MediumFrequency: 58.8%

Identify the Largest Outlier in an Array

Array Hash Table Counting Enumeration

Rank

#2563HardFrequency: 55.9%

Split Message Based on Limit

Rank

#4071MediumFrequency: 55.8%

Word Squares II

Array String Backtracking Sorting Enumeration

Rank

#3459HardFrequency: 55.1%

Find the Minimum Area to Cover All Ones II

Rank

#3469EasyFrequency: 55.1%

Maximum Height of a Triangle

Array Segment Tree Enumeration Prefix Sum

Rank

#3789HardFrequency: 55%

Maximize Subarrays After Removing One Conflicting Pair

Asked at LinkedIn

#10

Rank

#3277HardFrequency: 52.1%

Find the Number of Ways to Place People II

#11

Rank

#2889MediumFrequency: 49.9%

Number of Black Blocks

#12

Rank

#3751MediumFrequency: 48.9%

Maximum Frequency After Subarray Operation

Array Hash Table Dynamic Programming Greedy Enumeration Prefix Sum

#13

Rank

#2482MediumFrequency: 48.7%

Maximum Rows Covered by Columns

Array Backtracking Bit Manipulation Matrix Enumeration

#14

Rank

#3252EasyFrequency: 48.7%

Count the Number of Incremovable Subarrays I

Array Two Pointers Binary Search Enumeration

#15

Rank

#875MediumFrequency: 48%

Longest Mountain in Array

Array Two Pointers Dynamic Programming Enumeration

#16

Rank

#2339MediumFrequency: 47.5%

K Divisible Elements Subarrays

Array Hash Table Trie Rolling Hash Hash Function Enumeration

#17

Rank

#204MediumFrequency: 47.3%

Count Primes

Array Math Enumeration Number Theory Primality Test Sieve Theory Prime Number Sieve

#18

Rank

#856HardFrequency: 43.7%

Consecutive Numbers Sum

#19

Rank

#3402HardFrequency: 38.2%

Minimum Cost to Equalize Array

#20

Rank

#2272HardFrequency: 33.3%

Maximum Good People Based on Statements

#21

Rank

#4230MediumFrequency: 32.3%

Longest Arithmetic Sequence After Changing At Most One Element

#22

Rank

#2360HardFrequency: 31.3%

Substring With Largest Variance

#23

Rank

#3201MediumFrequency: 30.2%

Distribute Candies Among Children II

#24

Rank

#1993EasyFrequency: 29.1%

Sum of All Subset XOR Totals

Array Math Backtracking Bit Manipulation Combinatorics Enumeration

#25

Rank

#3263EasyFrequency: 29.1%

Divide an Array Into Subarrays With Minimum Cost I

#26

Rank

#2135HardFrequency: 27.7%

Maximum Number of Ways to Partition an Array

Array Hash Table Counting Enumeration Prefix Sum

#27

Rank

#1363EasyFrequency: 27.3%

Greatest English Letter in Upper and Lower Case

Hash Table String Enumeration

#28

Rank

#1743MediumFrequency: 27.3%

Count Substrings That Differ by One Character

#29

Rank

#2083EasyFrequency: 27.3%

Three Divisors

Math Enumeration Number Theory Prime Factorization Sieve Theory

#30

Rank

#2146MediumFrequency: 26.3%

Check if Word Can Be Placed In Crossword

#31

Rank

#2353HardFrequency: 26.3%

Maximum Score of a Node Sequence

Array Graph Theory Sorting Enumeration

#32

Rank

#3699MediumFrequency: 26.3%

Count Special Subsequences

Array Hash Table Math Enumeration

#33

Rank

#3299MediumFrequency: 25.1%

Find the Maximum Number of Elements in Subset

#34

Rank

#3278MediumFrequency: 24.4%

Find the Number of Ways to Place People I

#35

Rank

#3210MediumFrequency: 23.6%

Count Beautiful Substrings I

Hash Table Math String Enumeration Number Theory Prefix Sum

#36

Rank

#3741MediumFrequency: 23.3%

Reschedule Meetings for Maximum Free Time II

#37

Rank

#2215EasyFrequency: 22.1%

Finding 3-Digit Even Numbers

Array Hash Table Recursion Sorting Enumeration

#38

Rank

#1723HardFrequency: 21.9%

Maximum Number of Achievable Transfer Requests

#39

Rank

#2080MediumFrequency: 21.9%

Check if Move is Legal

#40

Rank

#3479MediumFrequency: 21.9%

Count the Number of Substrings With Dominant Ones

#41

Rank

#2140HardFrequency: 21.5%

Longest Subsequence Repeated k Times

Hash Table Two Pointers String Backtracking Counting Enumeration

#42

Rank

#681MediumFrequency: 20.9%

Next Closest Time

Hash Table String Backtracking Enumeration

#43

Rank

#3681MediumFrequency: 20.9%

Maximum Area Rectangle With Point Constraints I

Array Math Binary Indexed Tree Segment Tree Geometry Sorting Enumeration

#44

Rank

#3888HardFrequency: 20.9%

Maximize Subarray GCD Score

Array Math Enumeration Number Theory

#45

Rank

#900MediumFrequency: 20.9%

Reordered Power of 2

Hash Table Math Sorting Counting Enumeration

#46

Rank

#1887HardFrequency: 20%

Minimum Degree of a Connected Trio in a Graph

Graph Theory Enumeration

#47

Rank

#2541MediumFrequency: 20%

Sum of Number and Its Reverse

#48

Rank

#3199EasyFrequency: 20%

Distribute Candies Among Children I

#49

Rank

#1656EasyFrequency: 19.5%

Count Good Triplets

#50

Rank

#3626EasyFrequency: 19.5%

Smallest Divisible Digit Product I

#51

Rank

#3761HardFrequency: 19.5%

Maximum Difference Between Even and Odd Frequency II

String Sliding Window Enumeration Prefix Sum

#52

Rank

#1212MediumFrequency: 19.4%

Sequential Digits

Enumeration

#53

Rank

#942HardFrequency: 18%

Super Palindromes

#54

Rank

#2266MediumFrequency: 18%

Minimum Cost to Set Cooking Time

#55

Rank

#2849HardFrequency: 18%

Sum of Imbalance Numbers of All Subarrays

#56

Rank

#2528EasyFrequency: 18%

Number of Valid Clock Times

#57

Rank

#1747MediumFrequency: 18%

Lexicographically Smallest String After Applying Operations

String Depth-First Search Breadth-First Search Enumeration

#58

Rank

#3799EasyFrequency: 18%

Unique 3-Digit Even Numbers

Array Hash Table Recursion Enumeration

#59

Rank

#4020MediumFrequency: 18%

Lexicographically Smallest Permutation Greater Than Target

Hash Table String Greedy Counting Enumeration

#60

Rank

#4055MediumFrequency: 18%

Longest Balanced Substring I

Hash Table String Counting Enumeration

#61

Rank

#4057MediumFrequency: 18%

Total Waviness of Numbers in Range I

Math Dynamic Programming Enumeration

#62

Rank

#3805MediumFrequency: 18%

Maximize Active Section with Trade I

#63

Rank

#818EasyFrequency: 16.4%

Similar RGB Color

#64

Rank

#834MediumFrequency: 16.4%

Ambiguous Coordinates

String Backtracking Enumeration

#65

Rank

#2241HardFrequency: 16.4%

Recover the Original Array

Array Hash Table Two Pointers Sorting Enumeration

#66

Rank

#3314MediumFrequency: 16.4%

Most Frequent Prime

Array Hash Table Math Matrix Counting Enumeration Number Theory Primality Test Sieve Theory Prime Number Sieve

#67

Rank

#3361EasyFrequency: 16.4%

Latest Time You Can Obtain After Replacing Characters

#68

Rank

#2507EasyFrequency: 16.4%

Number of Common Factors

Math Enumeration Number Theory Euclidean Algorithm Greatest Common Divisor

#69

Rank

#2174MediumFrequency: 16.4%

Next Greater Numerically Balanced Number

Hash Table Math Backtracking Counting Enumeration

#70

Rank

#2037EasyFrequency: 16.4%

Count Square Sum Triples

#71

Rank

#2998EasyFrequency: 16.1%

Count Symmetric Integers

#72

Rank

#3683MediumFrequency: 16.1%

Find the Lexicographically Largest String From the Box I

Two Pointers String Enumeration

#73

Rank

#2170MediumFrequency: 14.6%

Count Number of Maximum Bitwise-OR Subsets

#74

Rank

#2202HardFrequency: 14.6%

Sum of k-Mirror Numbers

#75

Rank

#3548HardFrequency: 14.4%

Find the Count of Good Integers

Hash Table Math Combinatorics Enumeration

#76

Rank

#2837MediumFrequency: 13.2%

Minimum Operations to Make the Integer Zero

Bit Manipulation Brainteaser Enumeration

#77

Rank

#3849MediumFrequency: 12%

Equal Sum Grid Partition I

Array Matrix Enumeration Prefix Sum

#78

Rank

#3221EasyFrequency: 11.4%

Find the Peaks

#79

Rank

#3250MediumFrequency: 10.5%

Maximum Square Area by Removing Fences From a Field

#80

Rank

#3702EasyFrequency: 8.1%

Maximum Subarray With Equal Products

Array Math Sliding Window Enumeration Number Theory

#81

Rank

#3850HardFrequency: 8.1%

Equal Sum Grid Partition II

Array Hash Table Matrix Enumeration Prefix Sum

#82

Rank

#986MediumFrequency: 7.3%

Largest Time for Given Digits

Array String Backtracking Enumeration

#83

Rank

#2122EasyFrequency: 7.3%

Count Special Quadruplets

#84

Rank

#4318MediumFrequency: 7.3%

Valid Subarrays With Matching Sum Digits I

Array Hash Table Sliding Window Enumeration Prefix Sum

#85

Rank

#3104MediumFrequency: 7.2%

Happy Students

#86

Rank

#3820MediumFrequency: 7.2%

Number of Unique XOR Triplets II

Array Math Bit Manipulation Enumeration

#87

Rank

#2877MediumFrequency: 5.5%

Shortest String That Contains Three Strings

#88

Rank

#3579MediumFrequency: 5.5%

Maximum Possible Number by Binary Concatenation

Array Bit Manipulation Enumeration

#89

Rank

#3882HardFrequency: 5.5%

Partition Array for Maximum XOR and AND

Array Math Greedy Bit Manipulation Enumeration

#90

Rank

#3877MediumFrequency: 5.5%

Two-Letter Card Game

Array Hash Table String Counting Enumeration

#91

Rank

#2442EasyFrequency: 5%

Number of Arithmetic Triplets

Array Hash Table Two Pointers Enumeration

#92

Rank

#3868MediumFrequency: 5%

Find Maximum Area of a Triangle

Array Hash Table Math Greedy Geometry Enumeration

#93

Rank

#3793MediumFrequency: 5%

Longest Palindrome After Substring Concatenation I

Two Pointers String Dynamic Programming Enumeration

#94

Rank

#2844EasyFrequency: 5%

Sum of Squares of Special Elements

#95

Rank

#479HardFrequency: 5%

Largest Palindrome Product

#96

Rank

#2810MediumFrequency: 5%

Collecting Chocolates

#97

Rank

#3843MediumFrequency: 5%

Partition Array into Two Equal Product Subsets

Array Bit Manipulation Recursion Enumeration

#98

Rank

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Enumeration Interview Questions

Master 98 enumeration problems frequently asked in technical interviews. These questions test your understanding of enumerationconcepts and are essential for coding interview success.

Total Problems

Easy

Medium

Hard

Smallest Greater Multiple Made of Two Digits

Asked at PayPal

Rank

#3690HardFrequency: 71.5%

Smallest Substring With Identical Characters I

Array Binary Search Enumeration

Rank

#2337EasyFrequency: 59.4%

Remove Digit From Number to Maximize Result

Asked at Infosys

Rank

#3638HardFrequency: 59.3%

Minimum Operations to Make Character Frequencies Equal

Hash Table String Dynamic Programming Counting Enumeration

Rank

#3594MediumFrequency: 58.8%

Identify the Largest Outlier in an Array

Array Hash Table Counting Enumeration

Rank

#2563HardFrequency: 55.9%

Split Message Based on Limit

Rank

#4071MediumFrequency: 55.8%

Word Squares II

Array String Backtracking Sorting Enumeration

Rank

#3459HardFrequency: 55.1%

Find the Minimum Area to Cover All Ones II

Rank

#3469EasyFrequency: 55.1%

Maximum Height of a Triangle

Array Segment Tree Enumeration Prefix Sum

Rank

#3789HardFrequency: 55%

Maximize Subarrays After Removing One Conflicting Pair

Asked at LinkedIn

#10

Rank

#3277HardFrequency: 52.1%

Find the Number of Ways to Place People II

#11

Rank

#2889MediumFrequency: 49.9%

Number of Black Blocks

#12

Rank

#3751MediumFrequency: 48.9%

Maximum Frequency After Subarray Operation

Array Hash Table Dynamic Programming Greedy Enumeration Prefix Sum

#13

Rank

#2482MediumFrequency: 48.7%

Maximum Rows Covered by Columns

Array Backtracking Bit Manipulation Matrix Enumeration

#14

Rank

#3252EasyFrequency: 48.7%

Count the Number of Incremovable Subarrays I

Array Two Pointers Binary Search Enumeration

#15

Rank

#875MediumFrequency: 48%

Longest Mountain in Array

Array Two Pointers Dynamic Programming Enumeration

#16

Rank

#2339MediumFrequency: 47.5%

K Divisible Elements Subarrays

Array Hash Table Trie Rolling Hash Hash Function Enumeration

#17

Rank

#204MediumFrequency: 47.3%

Count Primes

Array Math Enumeration Number Theory Primality Test Sieve Theory Prime Number Sieve

#18

Rank

#856HardFrequency: 43.7%

Consecutive Numbers Sum

#19

Rank

#3402HardFrequency: 38.2%

Minimum Cost to Equalize Array

#20

Rank

#2272HardFrequency: 33.3%

Maximum Good People Based on Statements

#21

Rank

#4230MediumFrequency: 32.3%

Longest Arithmetic Sequence After Changing At Most One Element

#22

Rank

#2360HardFrequency: 31.3%

Substring With Largest Variance

#23

Rank

#3201MediumFrequency: 30.2%

Distribute Candies Among Children II

#24

Rank

#1993EasyFrequency: 29.1%

Sum of All Subset XOR Totals

Array Math Backtracking Bit Manipulation Combinatorics Enumeration

#25

Rank

#3263EasyFrequency: 29.1%

Divide an Array Into Subarrays With Minimum Cost I

#26

Rank

#2135HardFrequency: 27.7%

Maximum Number of Ways to Partition an Array

Array Hash Table Counting Enumeration Prefix Sum

#27

Rank

#1363EasyFrequency: 27.3%

Greatest English Letter in Upper and Lower Case

Hash Table String Enumeration

#28

Rank

#1743MediumFrequency: 27.3%

Count Substrings That Differ by One Character

#29

Rank

#2083EasyFrequency: 27.3%

Three Divisors

Math Enumeration Number Theory Prime Factorization Sieve Theory

#30

Rank

#2146MediumFrequency: 26.3%

Check if Word Can Be Placed In Crossword

#31

Rank

#2353HardFrequency: 26.3%

Maximum Score of a Node Sequence

Array Graph Theory Sorting Enumeration

#32

Rank

#3699MediumFrequency: 26.3%

Count Special Subsequences

Array Hash Table Math Enumeration

#33

Rank

#3299MediumFrequency: 25.1%

Find the Maximum Number of Elements in Subset

#34

Rank

#3278MediumFrequency: 24.4%

Find the Number of Ways to Place People I

#35

Rank

#3210MediumFrequency: 23.6%

Count Beautiful Substrings I

Hash Table Math String Enumeration Number Theory Prefix Sum

#36

Rank

#3741MediumFrequency: 23.3%

Reschedule Meetings for Maximum Free Time II

#37

Rank

#2215EasyFrequency: 22.1%

Finding 3-Digit Even Numbers

Array Hash Table Recursion Sorting Enumeration

#38

Rank

#1723HardFrequency: 21.9%

Maximum Number of Achievable Transfer Requests

#39

Rank

#2080MediumFrequency: 21.9%

Check if Move is Legal

#40

Rank

#3479MediumFrequency: 21.9%

Count the Number of Substrings With Dominant Ones

#41

Rank

#2140HardFrequency: 21.5%

Longest Subsequence Repeated k Times

Hash Table Two Pointers String Backtracking Counting Enumeration

#42

Rank

#681MediumFrequency: 20.9%

Next Closest Time

Hash Table String Backtracking Enumeration

#43

Rank

#3681MediumFrequency: 20.9%

Maximum Area Rectangle With Point Constraints I

Array Math Binary Indexed Tree Segment Tree Geometry Sorting Enumeration

#44

Rank

#3888HardFrequency: 20.9%

Maximize Subarray GCD Score

Array Math Enumeration Number Theory

#45

Rank

#900MediumFrequency: 20.9%

Reordered Power of 2

Hash Table Math Sorting Counting Enumeration

#46

Rank

#1887HardFrequency: 20%

Minimum Degree of a Connected Trio in a Graph

Graph Theory Enumeration

#47

Rank

#2541MediumFrequency: 20%

Sum of Number and Its Reverse

#48

Rank

#3199EasyFrequency: 20%

Distribute Candies Among Children I

#49

Rank

#1656EasyFrequency: 19.5%

Count Good Triplets

#50

Rank

#3626EasyFrequency: 19.5%

Smallest Divisible Digit Product I

#51

Rank

#3761HardFrequency: 19.5%

Maximum Difference Between Even and Odd Frequency II

String Sliding Window Enumeration Prefix Sum

#52

Rank

#1212MediumFrequency: 19.4%

Sequential Digits

Enumeration

#53

Rank

#942HardFrequency: 18%

Super Palindromes

#54

Rank

#2266MediumFrequency: 18%

Minimum Cost to Set Cooking Time

#55

Rank

#2849HardFrequency: 18%

Sum of Imbalance Numbers of All Subarrays

#56

Rank

#2528EasyFrequency: 18%

Number of Valid Clock Times

#57

Rank

#1747MediumFrequency: 18%

Lexicographically Smallest String After Applying Operations

String Depth-First Search Breadth-First Search Enumeration

#58

Rank

#3799EasyFrequency: 18%

Unique 3-Digit Even Numbers

Array Hash Table Recursion Enumeration

#59

Rank

#4020MediumFrequency: 18%

Lexicographically Smallest Permutation Greater Than Target

Hash Table String Greedy Counting Enumeration

#60

Rank

#4055MediumFrequency: 18%

Longest Balanced Substring I

Hash Table String Counting Enumeration

#61

Rank

#4057MediumFrequency: 18%

Total Waviness of Numbers in Range I

Math Dynamic Programming Enumeration

#62

Rank

#3805MediumFrequency: 18%

Maximize Active Section with Trade I

#63

Rank

#818EasyFrequency: 16.4%

Similar RGB Color

#64

Rank

#834MediumFrequency: 16.4%

Ambiguous Coordinates

String Backtracking Enumeration

#65

Rank

#2241HardFrequency: 16.4%

Recover the Original Array

Array Hash Table Two Pointers Sorting Enumeration

#66

Rank

#3314MediumFrequency: 16.4%

Most Frequent Prime

Array Hash Table Math Matrix Counting Enumeration Number Theory Primality Test Sieve Theory Prime Number Sieve

#67

Rank

#3361EasyFrequency: 16.4%

Latest Time You Can Obtain After Replacing Characters

#68

Rank

#2507EasyFrequency: 16.4%

Number of Common Factors

Math Enumeration Number Theory Euclidean Algorithm Greatest Common Divisor

#69

Rank

#2174MediumFrequency: 16.4%

Next Greater Numerically Balanced Number

Hash Table Math Backtracking Counting Enumeration

#70

Rank

#2037EasyFrequency: 16.4%

Count Square Sum Triples

#71

Rank

#2998EasyFrequency: 16.1%

Count Symmetric Integers

#72

Rank

#3683MediumFrequency: 16.1%

Find the Lexicographically Largest String From the Box I

Two Pointers String Enumeration

#73

Rank

#2170MediumFrequency: 14.6%

Count Number of Maximum Bitwise-OR Subsets

#74

Rank

#2202HardFrequency: 14.6%

Sum of k-Mirror Numbers

#75

Rank

#3548HardFrequency: 14.4%

Find the Count of Good Integers

Hash Table Math Combinatorics Enumeration

#76

Rank

#2837MediumFrequency: 13.2%

Minimum Operations to Make the Integer Zero

Bit Manipulation Brainteaser Enumeration

#77

Rank

#3849MediumFrequency: 12%

Equal Sum Grid Partition I

Array Matrix Enumeration Prefix Sum

#78

Rank

#3221EasyFrequency: 11.4%

Find the Peaks

#79

Rank

#3250MediumFrequency: 10.5%

Maximum Square Area by Removing Fences From a Field

#80

Rank

#3702EasyFrequency: 8.1%

Maximum Subarray With Equal Products

Array Math Sliding Window Enumeration Number Theory

#81

Rank

#3850HardFrequency: 8.1%

Equal Sum Grid Partition II

Array Hash Table Matrix Enumeration Prefix Sum

#82

Rank

#986MediumFrequency: 7.3%

Largest Time for Given Digits

Array String Backtracking Enumeration

#83

Rank

#2122EasyFrequency: 7.3%

Count Special Quadruplets

#84

Rank

#4318MediumFrequency: 7.3%

Valid Subarrays With Matching Sum Digits I

Array Hash Table Sliding Window Enumeration Prefix Sum

#85

Rank

#3104MediumFrequency: 7.2%

Happy Students

#86

Rank

#3820MediumFrequency: 7.2%

Number of Unique XOR Triplets II

Array Math Bit Manipulation Enumeration

#87

Rank

#2877MediumFrequency: 5.5%

Shortest String That Contains Three Strings

#88

Rank

#3579MediumFrequency: 5.5%

Maximum Possible Number by Binary Concatenation

Array Bit Manipulation Enumeration

#89

Rank

#3882HardFrequency: 5.5%

Partition Array for Maximum XOR and AND

Array Math Greedy Bit Manipulation Enumeration

#90

Rank

#3877MediumFrequency: 5.5%

Two-Letter Card Game

Array Hash Table String Counting Enumeration

#91

Rank

#2442EasyFrequency: 5%

Number of Arithmetic Triplets

Array Hash Table Two Pointers Enumeration

#92

Rank

#3868MediumFrequency: 5%

Find Maximum Area of a Triangle

Array Hash Table Math Greedy Geometry Enumeration

#93

Rank

#3793MediumFrequency: 5%

Longest Palindrome After Substring Concatenation I

Two Pointers String Dynamic Programming Enumeration

#94

Rank

#2844EasyFrequency: 5%

Sum of Squares of Special Elements

#95

Rank

#479HardFrequency: 5%

Largest Palindrome Product

#96

Rank

#2810MediumFrequency: 5%

Collecting Chocolates

#97

Rank

#3843MediumFrequency: 5%

Partition Array into Two Equal Product Subsets