Medium LeetCode Interview Questions

Hash Table String Sliding Window

#30

Rank

#3MediumFrequency: 84%

Longest Substring Without Repeating Characters

Asked at Microsoft

#31

Rank

#339MediumFrequency: 84%

Nested List Weight Sum

Asked at Meta

Depth-First Search Breadth-First Search

#32

Rank

#366MediumFrequency: 84%

Find Leaves of Binary Tree

Asked at LinkedIn

#33

Rank

#8MediumFrequency: 84%

String to Integer (atoi)

Asked at Databricks

String

#34

Rank

#198MediumFrequency: 84%

House Robber

Asked at Databricks

#35

Rank

#213MediumFrequency: 84%

House Robber II

Asked at Databricks

Array Hash Table Prefix Sum

#36

Rank

#752MediumFrequency: 84%

IP to CIDR

Asked at Databricks

String Bit Manipulation

#37

Rank

#560MediumFrequency: 81%

Subarray Sum Equals K

Asked at Meta

#38

Rank

#53MediumFrequency: 79%

Maximum Subarray

Asked at Microsoft

Array Divide and Conquer Dynamic Programming

#39

Rank

#236MediumFrequency: 79%

Lowest Common Ancestor of a Binary Tree

Asked at Meta

Tree Depth-First Search Breadth-First Search Binary Tree

#40

Rank

#199MediumFrequency: 76%

Binary Tree Right Side View

Asked at Meta

#41

Rank

#347MediumFrequency: 76%

Top K Frequent Elements

Asked at Meta

Array Hash Table Divide and Conquer Sorting Heap (Priority Queue)Bucket Sort Counting Quickselect

#42

Rank

#1713MediumFrequency: 76%

Dot Product of Two Sparse Vectors

Asked at Meta

Array Hash Table Two Pointers Design

#43

Rank

#3654MediumFrequency: 74%

Minimum Array Sum

Asked at Amazon

#44

Rank

#907MediumFrequency: 73%

Koko Eating Bananas

Asked at DoorDash

Array String Binary Search Trie Sorting Heap (Priority Queue)

#45

Rank

#1397MediumFrequency: 73%

Search Suggestions System

Asked at DoorDash

#46

Rank

#1783MediumFrequency: 73%

Ways to Make a Fair Array

Asked at DoorDash

Array Prefix Sum

#47

Rank

#778MediumFrequency: 72%

Reorganize String

Asked at Amazon

Hash Table String Greedy Sorting Heap (Priority Queue)Counting

#48

Rank

#56MediumFrequency: 72%

Merge Intervals

Asked at Meta

Array Sorting

#49

Rank

#39MediumFrequency: 72%

Combination Sum

Asked at TikTok

Array Backtracking

#50

Rank

#139MediumFrequency: 72%

Word Break

Asked at TikTok

Array Hash Table String Dynamic Programming Trie Memoization

#51

Rank

#1929MediumFrequency: 72%

Maximum Value at a Given Index in a Bounded Array

Asked at TikTok

Binary Search Greedy

#52

Rank

#235MediumFrequency: 72%

Lowest Common Ancestor of a Binary Search Tree

Asked at LinkedIn

Tree Depth-First Search Binary Search Tree Binary Tree

#53

Rank

#277MediumFrequency: 72%

Find the Celebrity

Asked at LinkedIn

Two Pointers Graph Interactive

#54

Rank

#2MediumFrequency: 71%

Add Two Numbers

Asked at Google

Linked List Math Recursion

#55

Rank

#1108MediumFrequency: 69%

Analyze User Website Visit Pattern

Asked at Amazon

Array Hash Table Sorting

#56

Rank

#1028MediumFrequency: 69%

Interval List Intersections

Asked at Meta

Array Two Pointers

#57

Rank

#129MediumFrequency: 68%

Sum Root to Leaf Numbers

Asked at Meta

Array Math Divide and Conquer Geometry Sorting Heap (Priority Queue)Quickselect

#58

Rank

#1014MediumFrequency: 68%

K Closest Points to Origin

Asked at Meta

#59

Rank

#1085MediumFrequency: 67%

The Earliest Moment When Everyone Become Friends

Asked at Google

Array Union Find Sorting

#60

Rank

#3639MediumFrequency: 67%

Zero Array Transformation I

Asked at Google

Array Prefix Sum

#61

Rank

#3647MediumFrequency: 67%

Zero Array Transformation III

Asked at Google

Array Greedy Sorting Heap (Priority Queue)Prefix Sum

#62

Rank

#138MediumFrequency: 67%

Copy List with Random Pointer

Asked at Amazon

Hash Table Linked List

#63

Rank

#2089MediumFrequency: 66%

Maximum Matrix Sum

Asked at Microsoft

Array Greedy Matrix

#64

Rank

#957MediumFrequency: 66%

Minimum Add to Make Parentheses Valid

Asked at Meta

String Stack Greedy

#65

Rank

#78MediumFrequency: 64%

Subsets

Asked at Meta

Array Backtracking Bit Manipulation

#66

Rank

#758MediumFrequency: 64%

Convert Binary Search Tree to Sorted Doubly Linked List

Asked at Meta

Linked List Stack Tree Depth-First Search Binary Search Tree Binary Tree Doubly-Linked List

#67

Rank

#893MediumFrequency: 64%

All Nodes Distance K in Binary Tree

Asked at Meta

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#68

Rank

#1909MediumFrequency: 64%

Buildings With an Ocean View

Asked at Meta

Array Stack Monotonic Stack

#69

Rank

#54MediumFrequency: 63%

Spiral Matrix

Asked at Uber

Array Matrix Simulation

#70

Rank

#79MediumFrequency: 63%

Word Search

Asked at Uber

Array String Backtracking Matrix

#71

Rank

#399MediumFrequency: 63%

Evaluate Division

Asked at Uber

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

#72

Rank

#772MediumFrequency: 63%

Construct Quad Tree

Asked at Uber

Array Divide and Conquer Tree Matrix

#73

Rank

#1549MediumFrequency: 63%

Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit

Asked at Uber

Array Queue Sliding Window Heap (Priority Queue)Ordered Set Monotonic Queue

#74

Rank

#34MediumFrequency: 63%

Find First and Last Position of Element in Sorted Array

Asked at LinkedIn

#75

Rank

#40MediumFrequency: 63%

Combination Sum II

Asked at LinkedIn

Array Backtracking

#76

Rank

#152MediumFrequency: 63%

Maximum Product Subarray

Asked at LinkedIn

Array Hash Table Two Pointers String Design

#77

Rank

#244MediumFrequency: 63%

Shortest Word Distance II

Asked at LinkedIn

#78

Rank

#31MediumFrequency: 62%

Next Permutation

Asked at Meta

Array Two Pointers

#79

Rank

#721MediumFrequency: 62%

Accounts Merge

Asked at Meta

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

#80

Rank

#253MediumFrequency: 62%

Meeting Rooms II

Asked at TikTok

Array Two Pointers Greedy Sorting Heap (Priority Queue)Prefix Sum

#81

Rank

#694MediumFrequency: 62%

Number of Distinct Islands

Asked at TikTok

Hash Table Depth-First Search Breadth-First Search Union Find Hash Function

#82

Rank

#2414MediumFrequency: 60%

Move Pieces to Obtain a String

Asked at Google

Two Pointers String

#83

Rank

#2868MediumFrequency: 60%

Continuous Subarrays

Asked at Google

Array Queue Sliding Window Heap (Priority Queue)Ordered Set Monotonic Queue

#84

Rank

#2891MediumFrequency: 60%

Maximum Beauty of an Array After Applying Operation

Asked at Google

Array Binary Search Sliding Window Sorting

#85

Rank

#15MediumFrequency: 60%

3Sum

Asked at Amazon

Array Two Pointers Sorting

#86

Rank

#55MediumFrequency: 60%

Jump Game

Asked at Amazon

Array Dynamic Programming Greedy

#87

Rank

#3018MediumFrequency: 60%

Make String a Subsequence Using Cyclic Increments

Asked at Amazon

Two Pointers String

#88

Rank

#133MediumFrequency: 60%

Clone Graph

Asked at Meta

Hash Table Depth-First Search Breadth-First Search Graph

#89

Rank

#807MediumFrequency: 60%

Custom Sort String

Asked at Meta

Hash Table String Sorting

#90

Rank

#850MediumFrequency: 57%

Insert into a Sorted Circular Linked List

Asked at Meta

Linked List

#91

Rank

#998MediumFrequency: 57%

Check Completeness of a Binary Tree

Asked at Meta

Tree Breadth-First Search Binary Tree

#92

Rank

#207MediumFrequency: 56%

Course Schedule

Asked at Google

Depth-First Search Breadth-First Search Graph Topological Sort

#93

Rank

#2164MediumFrequency: 56%

Two Best Non-Overlapping Events

Asked at Google

Array Binary Search Dynamic Programming Sorting Heap (Priority Queue)

#94

Rank

#6MediumFrequency: 56%

Zigzag Conversion

Asked at Amazon

String

#95

Rank

#17MediumFrequency: 56%

Letter Combinations of a Phone Number

Asked at Amazon

Hash Table String Backtracking

#96

Rank

#5MediumFrequency: 55%

Longest Palindromic Substring

Asked at Microsoft

Two Pointers String Dynamic Programming

#97

Rank

#12MediumFrequency: 55%

Integer to Roman

Asked at Microsoft

Hash Table Math String

#98

Rank

#18MediumFrequency: 55%

4Sum

Asked at Microsoft

Array Two Pointers Sorting

#99

Rank

#33MediumFrequency: 55%

Search in Rotated Sorted Array

Asked at Microsoft

Array Backtracking Bit Manipulation

#100

Rank

#90MediumFrequency: 55%

Subsets II

Asked at Microsoft

#101

Rank

#128MediumFrequency: 55%

Longest Consecutive Sequence

Asked at Microsoft

Array Hash Table Union Find

#102

Rank

#155MediumFrequency: 55%

Min Stack

Asked at Microsoft

Stack Design

#103

Rank

#167MediumFrequency: 55%

Two Sum II - Input Array Is Sorted

Asked at Microsoft

Array Two Pointers Binary Search

#104

Rank

#291MediumFrequency: 55%

Word Pattern II

Asked at Microsoft

Hash Table String Backtracking

#105

Rank

#567MediumFrequency: 55%

Permutation in String

Asked at Microsoft

Hash Table Two Pointers String Sliding Window

#106

Rank

#1036MediumFrequency: 55%

Rotting Oranges

Asked at Microsoft

Array Breadth-First Search Matrix

#107

Rank

#1147MediumFrequency: 55%

Flip Columns For Maximum Number of Equal Rows

Asked at Microsoft

Array Hash Table Matrix

#108

Rank

#22MediumFrequency: 53%

Generate Parentheses

Asked at Google

String Dynamic Programming Backtracking

#109

Rank

#114MediumFrequency: 53%

Flatten Binary Tree to Linked List

Asked at Google

Linked List Stack Tree Depth-First Search Binary Tree

#110

Rank

#2300MediumFrequency: 53%

Construct String With Repeat Limit

Asked at Google

Hash Table String Greedy Heap (Priority Queue)Counting

#111

Rank

#380MediumFrequency: 51%

Insert Delete GetRandom O(1)

Asked at Amazon

Array Hash Table Math Design Randomized

#112

Rank

#1056MediumFrequency: 51%

Capacity To Ship Packages Within D Days

Asked at Amazon

Linked List Tree Depth-First Search Breadth-First Search Binary Tree

#113

Rank

#116MediumFrequency: 51%

Populating Next Right Pointers in Each Node

Asked at Meta

#114

Rank

#173MediumFrequency: 51%

Binary Search Tree Iterator

Asked at Meta

Stack Tree Design Binary Search Tree Binary Tree Iterator

#115

Rank

#398MediumFrequency: 51%

Random Pick Index

Asked at Meta

Hash Table Math Reservoir Sampling Randomized

#116

Rank

#7MediumFrequency: 48%

Reverse Integer

Asked at Google

Math

#117

Rank

#976MediumFrequency: 48%

Minimum Area Rectangle

Asked at Google

Array Hash Table Math Geometry Sorting

#118

Rank

#1886MediumFrequency: 48%

Minimum Limit of Balls in a Bag

Asked at Google

Array Two Pointers String Simulation

#119

Rank

#2232MediumFrequency: 48%

Adding Spaces to a String

Asked at Google

#120

Rank

#3643MediumFrequency: 48%

Zero Array Transformation II

Asked at Google

Array Binary Search Prefix Sum

#121

Rank

#48MediumFrequency: 47%

Rotate Image

Asked at Meta

Array Math Matrix

#122

Rank

#545MediumFrequency: 47%

Boundary of Binary Tree

Asked at Meta

Array Dynamic Programming Greedy

#123

Rank

#122MediumFrequency: 45%

Best Time to Buy and Sell Stock II

Asked at Amazon

#124

Rank

#151MediumFrequency: 45%

Reverse Words in a String

Asked at Amazon

Two Pointers String

#125

Rank

#373MediumFrequency: 45%

Find K Pairs with Smallest Sums

Asked at Amazon

Array Heap (Priority Queue)

#126

Rank

#19MediumFrequency: 43%

Remove Nth Node From End of List

Asked at Meta

Linked List Two Pointers

#127

Rank

#249MediumFrequency: 43%

Group Shifted Strings

Asked at Meta

Array Hash Table String

#128

Rank

#325MediumFrequency: 43%

Maximum Size Subarray Sum Equals k

Asked at Meta

Array Hash Table Prefix Sum

#129

Rank

#498MediumFrequency: 43%

Diagonal Traverse

Asked at Meta

Array Matrix Simulation

#130

Rank

#523MediumFrequency: 43%

Continuous Subarray Sum

Asked at Meta

Array Hash Table Math Prefix Sum

#131

Rank

#670MediumFrequency: 43%

Maximum Swap

Asked at Meta

Math Greedy

#132

Rank

#11MediumFrequency: 42%

Container With Most Water

Asked at Google

Array Two Pointers Greedy

#133

Rank

#46MediumFrequency: 42%

Permutations

Asked at Google

Array Backtracking

#134

Rank

#62MediumFrequency: 42%

Unique Paths

Asked at Google

Math Dynamic Programming Combinatorics

#135

Rank

#63MediumFrequency: 42%

Unique Paths II

Asked at Google

Array Dynamic Programming Matrix

#136

Rank

#75MediumFrequency: 42%

Sort Colors

Asked at Google

Array Two Pointers Sorting

#137

Rank

#179MediumFrequency: 42%

Largest Number

Asked at Google

Array String Greedy Sorting

#138

Rank

#394MediumFrequency: 42%

Decode String

Asked at Google

String Stack Recursion

#139

Rank

#424MediumFrequency: 42%

Longest Repeating Character Replacement

Asked at Google

Hash Table String Sliding Window

#140

Rank

#518MediumFrequency: 42%

Coin Change II

Asked at Google