Design Interview Questions

Rank

#716HardFrequency: 100%

Max Stack

Linked List Stack Design Doubly-Linked List Ordered Set

Rank

#362MediumFrequency: 100%

Design Hit Counter

Array Binary Search Design Queue Data Stream

Rank

#432HardFrequency: 93.8%

All O`one Data Structure

Rank

#348MediumFrequency: 93.6%

Design Tic-Tac-Toe

Array Hash Table Design Matrix Simulation

Rank

#251MediumFrequency: 85.6%

Flatten 2D Vector

Array Two Pointers Design Iterator

Rank

#1366MediumFrequency: 83.2%

First Unique Number

Array Hash Table Design Queue Data Stream

Rank

#244MediumFrequency: 82.3%

Shortest Word Distance II

Array Hash Table Two Pointers String Design

Rank

#1023MediumFrequency: 79.9%

Time Based Key-Value Store

Hash Table String Binary Search Design

Rank

#1713MediumFrequency: 79.6%

Dot Product of Two Sparse Vectors

Array Hash Table Two Pointers Design Linear Algebra

#10

Rank

#2023HardFrequency: 79.4%

Design Movie Rental System

Array Hash Table Design Heap (Priority Queue)Ordered Set

#11

Rank

#460HardFrequency: 78.9%

LFU Cache

#12

Rank

#631HardFrequency: 78.6%

Design Excel Sum Formula

Array Hash Table String Graph Theory Design Topological Sort Matrix

#13

Rank

#380MediumFrequency: 76.2%

Insert Delete GetRandom O(1)

#14

Rank

#729MediumFrequency: 73.4%

My Calendar I

Array Binary Search Design Segment Tree Ordered Set

#15

Rank

#346EasyFrequency: 73.1%

Moving Average from Data Stream

Array Design Queue Data Stream

#16

Rank

#1125MediumFrequency: 72.7%

Design File System

#17

Rank

#2169MediumFrequency: 72.1%

Simple Bank System

#18

Rank

#1249MediumFrequency: 66.8%

Snapshot Array

Array Hash Table Binary Search Design Persistent Data Structure

#19

Rank

#295HardFrequency: 66.4%

Find Median from Data Stream

Asked at PayPal

Two Pointers Design Sorting Heap (Priority Queue)Data Stream

#20

Rank

#588HardFrequency: 65.6%

Design In-Memory File System

Hash Table String Design Trie Sorting

#21

Rank

#936MediumFrequency: 65.2%

RLE Iterator

Array Design Counting Iterator

#22

Rank

#297HardFrequency: 63.4%

Serialize and Deserialize Binary Tree

String Tree Depth-First Search Breadth-First Search Design Binary Tree

#23

Rank

#969EasyFrequency: 63.3%

Number of Recent Calls

Design Queue Data Stream

#24

Rank

#860MediumFrequency: 62.5%

Design Circular Queue

#25

Rank

#155MediumFrequency: 61.8%

Min Stack

Stack Design

#26

Rank

#817EasyFrequency: 61.4%

Design HashMap

#27

Rank

#173MediumFrequency: 60.9%

Binary Search Tree Iterator

Stack Tree Design Binary Search Tree Binary Tree Iterator

#28

Rank

#381HardFrequency: 59.7%

Insert Delete GetRandom O(1) - Duplicates allowed

#29

Rank

#1905MediumFrequency: 58%

Design Authentication Manager

#30

Rank

#931HardFrequency: 57.5%

Maximum Frequency Stack

Hash Table Stack Design Ordered Set

#31

Rank

#2357HardFrequency: 56.3%

Count Integers in Intervals

#32

Rank

#384MediumFrequency: 55.9%

Shuffle an Array

Array Math Design Randomized

#33

Rank

#885MediumFrequency: 55.1%

Exam Room

Design Heap (Priority Queue)Ordered Set

#34

Rank

#208MediumFrequency: 55%

Implement Trie (Prefix Tree)

#35

Rank

#284MediumFrequency: 55%

Peeking Iterator

Array Design Iterator

#36

Rank

#211MediumFrequency: 54.4%

Design Add and Search Words Data Structure

String Depth-First Search Design Trie

#37

Rank

#359EasyFrequency: 52.3%

Logger Rate Limiter

Hash Table Design Data Stream

#38

Rank

#303EasyFrequency: 51.8%

Range Sum Query - Immutable

Asked at Infosys

Array Design Prefix Sum

#39

Rank

#341MediumFrequency: 51%

Flatten Nested List Iterator

Stack Tree Depth-First Search Design Queue Iterator

#40

Rank

#535MediumFrequency: 49.9%

Encode and Decode TinyURL

Hash Table String Design Hash Function

#41

Rank

#232EasyFrequency: 48.7%

Implement Queue using Stacks

#42

Rank

#937MediumFrequency: 45.8%

Online Stock Span

Stack Design Monotonic Stack Data Stream

#43

Rank

#170EasyFrequency: 44.7%

Two Sum III - Data structure design

Array Hash Table Two Pointers Design Data Stream

#44

Rank

#677MediumFrequency: 43.2%

Map Sum Pairs

#45

Rank

#2587MediumFrequency: 43%

Design Memory Allocator

#46

Rank

#715HardFrequency: 42.7%

Range Module

#47

Rank

#1708EasyFrequency: 41.4%

Design Parking System

Design Simulation Counting

#48

Rank

#355MediumFrequency: 41.2%

Design Twitter

Hash Table Linked List Design Heap (Priority Queue)

#49

Rank

#789EasyFrequency: 40.8%

Kth Largest Element in a Stream

Tree Design Binary Search Tree Heap (Priority Queue)Binary Tree Data Stream

#50

Rank

#1953HardFrequency: 39.5%

Finding MK Average

Design Queue Heap (Priority Queue)Data Stream Ordered Set Treap

#51

Rank

#642HardFrequency: 39.1%

Design Search Autocomplete System

String Depth-First Search Design Trie Sorting Heap (Priority Queue)Data Stream

#52

Rank

#225EasyFrequency: 38.2%

Implement Stack using Queues

#53

Rank

#1995MediumFrequency: 35.5%

Finding Pairs With a Certain Sum

#54

Rank

#635MediumFrequency: 35%

Design Log Storage System

Hash Table String Design Ordered Set

#55

Rank

#1477MediumFrequency: 33%

Product of the Last K Numbers

Array Math Design Data Stream Prefix Sum

#56

Rank

#1497MediumFrequency: 32.4%

Design a Stack With Increment Operation

Array Stack Design

#57

Rank

#2139MediumFrequency: 31.1%

Detect Squares

Array Hash Table Design Counting Data Stream

#58

Rank

#838MediumFrequency: 31.1%

Design Linked List

#59

Rank

#2434MediumFrequency: 30.4%

Design a Number Container System

#60

Rank

#271MediumFrequency: 30.4%

Encode and Decode Strings

Array String Design

#61

Rank

#304MediumFrequency: 30.4%

Range Sum Query 2D - Immutable

Array Design Matrix Prefix Sum

#62

Rank

#1582MediumFrequency: 29.5%

Design Browser History

Array Linked List Stack Design Doubly-Linked List Data Stream

#63

Rank

#731MediumFrequency: 29.5%

My Calendar II

Array Binary Search Design Segment Tree Prefix Sum Ordered Set

#64

Rank

#3678MediumFrequency: 29.5%

Design Task Manager

#65

Rank

#2389HardFrequency: 28.1%

Design a Text Editor

Linked List String Stack Design Simulation Doubly-Linked List

#66

Rank

#1768MediumFrequency: 27.8%

Design an Expression Tree With Evaluate Function

Array Math Stack Tree Design Binary Tree

#67

Rank

#1176MediumFrequency: 27.8%

Design A Leaderboard

Hash Table Design Sorting

#68

Rank

#353MediumFrequency: 27.7%

Design Snake Game

Array Hash Table Design Queue Simulation

#69

Rank

#1337HardFrequency: 27.3%

Design Skiplist

#70

Rank

#1296HardFrequency: 27.2%

Kth Ancestor of a Tree Node

Binary Search Dynamic Programming Bit Manipulation Tree Depth-First Search Breadth-First Search Design Binary Lifting

#71

Rank

#2413MediumFrequency: 26.5%

Smallest Number in Infinite Set

#72

Rank

#2161MediumFrequency: 25.4%

Stock Price Fluctuation

Hash Table Design Heap (Priority Queue)Data Stream Ordered Set

#73

Rank

#449MediumFrequency: 25.1%

Serialize and Deserialize BST

String Tree Depth-First Search Breadth-First Search Design Binary Search Tree Binary Tree

#74

Rank

#3710HardFrequency: 25.1%

Design an Array Statistics Tracker

Hash Table Binary Search Design Queue Heap (Priority Queue)Data Stream Ordered Set

#75

Rank

#1729MediumFrequency: 25.1%

Binary Search Tree Iterator II

Stack Tree Design Binary Search Tree Binary Tree Iterator

#76

Rank

#2429MediumFrequency: 23.6%

Design a Food Rating System

Array Hash Table String Design Heap (Priority Queue)Ordered Set

#77

Rank

#746HardFrequency: 23.4%

Prefix and Suffix Search

#78

Rank

#1459MediumFrequency: 23.4%

Apply Discount Every n Orders

#79

Rank

#308MediumFrequency: 23.3%

Range Sum Query 2D - Mutable

Array Design Binary Indexed Tree Segment Tree Matrix Sqrt Decomposition

#80

Rank

#676MediumFrequency: 22.1%

Implement Magic Dictionary

Hash Table String Depth-First Search Design Trie

#81

Rank

#947MediumFrequency: 22.1%

Online Election

Array Hash Table Binary Search Design

#82

Rank

#1097HardFrequency: 22.1%

Stream of Characters

Array String Design Trie Data Stream Aho–Corasick Algorithm

#83

Rank

#2555MediumFrequency: 21.9%

Design SQL

#84

Rank

#4118MediumFrequency: 21.5%

Design Ride Sharing System

Hash Table Design Queue Data Stream

#85

Rank

#1767MediumFrequency: 20%

Design Front Middle Back Queue

Array Linked List Design Queue Doubly-Linked List Data Stream

#86

Rank

#2207HardFrequency: 20%

Sequentially Ordinal Rank Tracker

Design Heap (Priority Queue)Data Stream Ordered Set

#87

Rank

#604EasyFrequency: 19.5%

Design Compressed String Iterator

Array String Design Iterator

#88

Rank

#732HardFrequency: 19.5%

My Calendar III

Binary Search Design Segment Tree Prefix Sum Ordered Set

#89

Rank

#2512MediumFrequency: 19.5%

Longest Uploaded Prefix

Hash Table Binary Search Union-Find Design Binary Indexed Tree Segment Tree Heap (Priority Queue)Ordered Set

#90

Rank

#1722MediumFrequency: 18%

Throne Inheritance

Hash Table Tree Depth-First Search Design

#91

Rank

#1728HardFrequency: 18%

Fancy Sequence

Math Design Segment Tree Number Theory Fermat's Little Theorem

#92

Rank

#2104MediumFrequency: 18%

Operations on Tree

Array Hash Table Tree Depth-First Search Breadth-First Search Design

#93

Rank

#379MediumFrequency: 18%

Design Phone Directory

Array Hash Table Linked List Design Queue

#94

Rank

#816EasyFrequency: 18%

Design HashSet

#95

Rank

#281MediumFrequency: 16.4%

Zigzag Iterator

Array Design Queue Iterator

#96

Rank

#288MediumFrequency: 16.4%

Unique Word Abbreviation

#97

Rank

#955MediumFrequency: 16.4%

Complete Binary Tree Inserter

Tree Breadth-First Search Design Binary Tree

#98

Rank

#1211MediumFrequency: 16.4%

Iterator for Combination

String Backtracking Design Iterator

#99

Rank

#1387MediumFrequency: 16.4%

Find Elements in a Contaminated Binary Tree

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

#100

Rank

#1865HardFrequency: 16.4%

Checking Existence of Edge Length Limited Paths II

Depth-First Search Union-Find Graph Theory Design Sorting Heap (Priority Queue)Minimum Spanning Tree

#101

Rank

#1903MediumFrequency: 16.4%

Design Most Recently Used Queue

Array Linked List Divide and Conquer Design Simulation Doubly-Linked List Sqrt Decomposition Treap Splay Tree

#102

Rank

#2352MediumFrequency: 16.4%

Design an ATM Machine

Array Greedy Design

#103

Rank

#2380HardFrequency: 16.4%

Booking Concert Tickets in Groups

Binary Search Design Binary Indexed Tree Segment Tree

#104

Rank

#2396HardFrequency: 16.4%

Design Video Sharing Platform

Hash Table Design Heap (Priority Queue)

#105

Rank

#859MediumFrequency: 14.6%

Design Circular Deque

#106

Rank

#2178MediumFrequency: 14.6%

Walking Robot Simulation II

Design Simulation

#107

Rank

#307MediumFrequency: 10.5%

Range Sum Query - Mutable

Array Divide and Conquer Design Binary Indexed Tree Segment Tree Sqrt Decomposition

#108

Rank

#1512MediumFrequency: 10.3%

Design Underground System

Hash Table String Design

#109

Rank

#352HardFrequency: 8.1%

Data Stream as Disjoint Intervals

Hash Table Binary Search Union-Find Design Data Stream Ordered Set

#110

Rank

#1955MediumFrequency: 8.1%

Seat Reservation Manager

Design Heap (Priority Queue)

#111

Rank

#1470MediumFrequency: 8.1%

Tweet Counts Per Frequency

Hash Table String Binary Search Design Sorting Ordered Set

#112

Rank

#3797MediumFrequency: 8.1%

Design Spreadsheet

Array Hash Table String Design Matrix

#113

Rank

#3827MediumFrequency: 7.3%

Implement Router

Array Hash Table Binary Search Design Queue Ordered Set

#114

Rank

#1294MediumFrequency: 7.3%

Range Frequency Queries

Array Hash Table Binary Search Design Segment Tree

#115

Rank

#1270HardFrequency: 7.2%

Dinner Plate Stacks

Hash Table Stack Design Heap (Priority Queue)

#116

Rank

#4067MediumFrequency: 5.5%

Design Auction System

#117

Rank

#1572MediumFrequency: 5%

Subrectangle Queries

Array Design Matrix

#118

Rank

#1433HardFrequency: 5%

Encrypt and Decrypt Strings

#119

Rank

#1949MediumFrequency: 5%

Implement Trie II (Prefix Tree)

#120

Rank

#4059MediumFrequency: 5%

Design Exam Scores Tracker

Array Binary Search Design Prefix Sum

#121

Rank

#1775EasyFrequency: 5%

Design an Ordered Stream

Array Hash Table Design Data Stream

#122

Rank

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Design Interview Questions

Master 122 design problems frequently asked in technical interviews. These questions test your understanding of designconcepts and are essential for coding interview success.

122

Total Problems

Easy

Medium

Hard

LRU Cache

Rank

#716HardFrequency: 100%

Max Stack

Linked List Stack Design Doubly-Linked List Ordered Set

Rank

#362MediumFrequency: 100%

Design Hit Counter

Array Binary Search Design Queue Data Stream

Rank

#432HardFrequency: 93.8%

All O`one Data Structure

Rank

#348MediumFrequency: 93.6%

Design Tic-Tac-Toe

Array Hash Table Design Matrix Simulation

Rank

#251MediumFrequency: 85.6%

Flatten 2D Vector

Array Two Pointers Design Iterator

Rank

#1366MediumFrequency: 83.2%

First Unique Number

Array Hash Table Design Queue Data Stream

Rank

#244MediumFrequency: 82.3%

Shortest Word Distance II

Array Hash Table Two Pointers String Design

Rank

#1023MediumFrequency: 79.9%

Time Based Key-Value Store

Hash Table String Binary Search Design

Rank

#1713MediumFrequency: 79.6%

Dot Product of Two Sparse Vectors

Array Hash Table Two Pointers Design Linear Algebra

#10

Rank

#2023HardFrequency: 79.4%

Design Movie Rental System

Array Hash Table Design Heap (Priority Queue)Ordered Set

#11

Rank

#460HardFrequency: 78.9%

LFU Cache

#12

Rank

#631HardFrequency: 78.6%

Design Excel Sum Formula

Array Hash Table String Graph Theory Design Topological Sort Matrix

#13

Rank

#380MediumFrequency: 76.2%

Insert Delete GetRandom O(1)

#14

Rank

#729MediumFrequency: 73.4%

My Calendar I

Array Binary Search Design Segment Tree Ordered Set

#15

Rank

#346EasyFrequency: 73.1%

Moving Average from Data Stream

Array Design Queue Data Stream

#16

Rank

#1125MediumFrequency: 72.7%

Design File System

#17

Rank

#2169MediumFrequency: 72.1%

Simple Bank System

#18

Rank

#1249MediumFrequency: 66.8%

Snapshot Array

Array Hash Table Binary Search Design Persistent Data Structure

#19

Rank

#295HardFrequency: 66.4%

Find Median from Data Stream

Asked at PayPal

Two Pointers Design Sorting Heap (Priority Queue)Data Stream

#20

Rank

#588HardFrequency: 65.6%

Design In-Memory File System

Hash Table String Design Trie Sorting

#21

Rank

#936MediumFrequency: 65.2%

RLE Iterator

Array Design Counting Iterator

#22

Rank

#297HardFrequency: 63.4%

Serialize and Deserialize Binary Tree

String Tree Depth-First Search Breadth-First Search Design Binary Tree

#23

Rank

#969EasyFrequency: 63.3%

Number of Recent Calls

Design Queue Data Stream

#24

Rank

#860MediumFrequency: 62.5%

Design Circular Queue

#25

Rank

#155MediumFrequency: 61.8%

Min Stack

Stack Design

#26

Rank

#817EasyFrequency: 61.4%

Design HashMap

#27

Rank

#173MediumFrequency: 60.9%

Binary Search Tree Iterator

Stack Tree Design Binary Search Tree Binary Tree Iterator

#28

Rank

#381HardFrequency: 59.7%

Insert Delete GetRandom O(1) - Duplicates allowed

#29

Rank

#1905MediumFrequency: 58%

Design Authentication Manager

#30

Rank

#931HardFrequency: 57.5%

Maximum Frequency Stack

Hash Table Stack Design Ordered Set

#31

Rank

#2357HardFrequency: 56.3%

Count Integers in Intervals

#32

Rank

#384MediumFrequency: 55.9%

Shuffle an Array

Array Math Design Randomized

#33

Rank

#885MediumFrequency: 55.1%

Exam Room

Design Heap (Priority Queue)Ordered Set

#34

Rank

#208MediumFrequency: 55%

Implement Trie (Prefix Tree)

#35

Rank

#284MediumFrequency: 55%

Peeking Iterator

Array Design Iterator

#36

Rank

#211MediumFrequency: 54.4%

Design Add and Search Words Data Structure

String Depth-First Search Design Trie

#37

Rank

#359EasyFrequency: 52.3%

Logger Rate Limiter

Hash Table Design Data Stream

#38

Rank

#303EasyFrequency: 51.8%

Range Sum Query - Immutable

Asked at Infosys

Array Design Prefix Sum

#39

Rank

#341MediumFrequency: 51%

Flatten Nested List Iterator

Stack Tree Depth-First Search Design Queue Iterator

#40

Rank

#535MediumFrequency: 49.9%

Encode and Decode TinyURL

Hash Table String Design Hash Function

#41

Rank

#232EasyFrequency: 48.7%

Implement Queue using Stacks

#42

Rank

#937MediumFrequency: 45.8%

Online Stock Span

Stack Design Monotonic Stack Data Stream

#43

Rank

#170EasyFrequency: 44.7%

Two Sum III - Data structure design

Array Hash Table Two Pointers Design Data Stream

#44

Rank

#677MediumFrequency: 43.2%

Map Sum Pairs

#45

Rank

#2587MediumFrequency: 43%

Design Memory Allocator

#46

Rank

#715HardFrequency: 42.7%

Range Module

#47

Rank

#1708EasyFrequency: 41.4%

Design Parking System

Design Simulation Counting

#48

Rank

#355MediumFrequency: 41.2%

Design Twitter

Hash Table Linked List Design Heap (Priority Queue)

#49

Rank

#789EasyFrequency: 40.8%

Kth Largest Element in a Stream

Tree Design Binary Search Tree Heap (Priority Queue)Binary Tree Data Stream

#50

Rank

#1953HardFrequency: 39.5%

Finding MK Average

Design Queue Heap (Priority Queue)Data Stream Ordered Set Treap

#51

Rank

#642HardFrequency: 39.1%

Design Search Autocomplete System

String Depth-First Search Design Trie Sorting Heap (Priority Queue)Data Stream

#52

Rank

#225EasyFrequency: 38.2%

Implement Stack using Queues

#53

Rank

#1995MediumFrequency: 35.5%

Finding Pairs With a Certain Sum

#54

Rank

#635MediumFrequency: 35%

Design Log Storage System

Hash Table String Design Ordered Set

#55

Rank

#1477MediumFrequency: 33%

Product of the Last K Numbers

Array Math Design Data Stream Prefix Sum

#56

Rank

#1497MediumFrequency: 32.4%

Design a Stack With Increment Operation

Array Stack Design

#57

Rank

#2139MediumFrequency: 31.1%

Detect Squares

Array Hash Table Design Counting Data Stream

#58

Rank

#838MediumFrequency: 31.1%

Design Linked List

#59

Rank

#2434MediumFrequency: 30.4%

Design a Number Container System

#60

Rank

#271MediumFrequency: 30.4%

Encode and Decode Strings

Array String Design

#61

Rank

#304MediumFrequency: 30.4%

Range Sum Query 2D - Immutable

Array Design Matrix Prefix Sum

#62

Rank

#1582MediumFrequency: 29.5%

Design Browser History

Array Linked List Stack Design Doubly-Linked List Data Stream

#63

Rank

#731MediumFrequency: 29.5%

My Calendar II

Array Binary Search Design Segment Tree Prefix Sum Ordered Set

#64

Rank

#3678MediumFrequency: 29.5%

Design Task Manager

#65

Rank

#2389HardFrequency: 28.1%

Design a Text Editor

Linked List String Stack Design Simulation Doubly-Linked List

#66

Rank

#1768MediumFrequency: 27.8%

Design an Expression Tree With Evaluate Function

Array Math Stack Tree Design Binary Tree

#67

Rank

#1176MediumFrequency: 27.8%

Design A Leaderboard

Hash Table Design Sorting

#68

Rank

#353MediumFrequency: 27.7%

Design Snake Game

Array Hash Table Design Queue Simulation

#69

Rank

#1337HardFrequency: 27.3%

Design Skiplist

#70

Rank

#1296HardFrequency: 27.2%

Kth Ancestor of a Tree Node

Binary Search Dynamic Programming Bit Manipulation Tree Depth-First Search Breadth-First Search Design Binary Lifting

#71

Rank

#2413MediumFrequency: 26.5%

Smallest Number in Infinite Set

#72

Rank

#2161MediumFrequency: 25.4%

Stock Price Fluctuation

Hash Table Design Heap (Priority Queue)Data Stream Ordered Set

#73

Rank

#449MediumFrequency: 25.1%

Serialize and Deserialize BST

String Tree Depth-First Search Breadth-First Search Design Binary Search Tree Binary Tree

#74

Rank

#3710HardFrequency: 25.1%

Design an Array Statistics Tracker

Hash Table Binary Search Design Queue Heap (Priority Queue)Data Stream Ordered Set

#75

Rank

#1729MediumFrequency: 25.1%

Binary Search Tree Iterator II

Stack Tree Design Binary Search Tree Binary Tree Iterator

#76

Rank

#2429MediumFrequency: 23.6%

Design a Food Rating System

Array Hash Table String Design Heap (Priority Queue)Ordered Set

#77

Rank

#746HardFrequency: 23.4%

Prefix and Suffix Search

#78

Rank

#1459MediumFrequency: 23.4%

Apply Discount Every n Orders

#79

Rank

#308MediumFrequency: 23.3%

Range Sum Query 2D - Mutable

Array Design Binary Indexed Tree Segment Tree Matrix Sqrt Decomposition

#80

Rank

#676MediumFrequency: 22.1%

Implement Magic Dictionary

Hash Table String Depth-First Search Design Trie

#81

Rank

#947MediumFrequency: 22.1%

Online Election

Array Hash Table Binary Search Design

#82

Rank

#1097HardFrequency: 22.1%

Stream of Characters

Array String Design Trie Data Stream Aho–Corasick Algorithm

#83

Rank

#2555MediumFrequency: 21.9%

Design SQL

#84

Rank

#4118MediumFrequency: 21.5%

Design Ride Sharing System

Hash Table Design Queue Data Stream

#85

Rank

#1767MediumFrequency: 20%

Design Front Middle Back Queue

Array Linked List Design Queue Doubly-Linked List Data Stream

#86

Rank

#2207HardFrequency: 20%

Sequentially Ordinal Rank Tracker

Design Heap (Priority Queue)Data Stream Ordered Set

#87

Rank

#604EasyFrequency: 19.5%

Design Compressed String Iterator

Array String Design Iterator

#88

Rank

#732HardFrequency: 19.5%

My Calendar III

Binary Search Design Segment Tree Prefix Sum Ordered Set

#89

Rank

#2512MediumFrequency: 19.5%

Longest Uploaded Prefix

Hash Table Binary Search Union-Find Design Binary Indexed Tree Segment Tree Heap (Priority Queue)Ordered Set

#90

Rank

#1722MediumFrequency: 18%

Throne Inheritance

Hash Table Tree Depth-First Search Design

#91

Rank

#1728HardFrequency: 18%

Fancy Sequence

Math Design Segment Tree Number Theory Fermat's Little Theorem

#92

Rank

#2104MediumFrequency: 18%

Operations on Tree

Array Hash Table Tree Depth-First Search Breadth-First Search Design

#93

Rank

#379MediumFrequency: 18%

Design Phone Directory

Array Hash Table Linked List Design Queue

#94

Rank

#816EasyFrequency: 18%

Design HashSet

#95

Rank

#281MediumFrequency: 16.4%

Zigzag Iterator

Array Design Queue Iterator

#96

Rank

#288MediumFrequency: 16.4%

Unique Word Abbreviation

#97

Rank

#955MediumFrequency: 16.4%

Complete Binary Tree Inserter

Tree Breadth-First Search Design Binary Tree

#98

Rank

#1211MediumFrequency: 16.4%

Iterator for Combination

String Backtracking Design Iterator

#99

Rank

#1387MediumFrequency: 16.4%

Find Elements in a Contaminated Binary Tree

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

#100

Rank

#1865HardFrequency: 16.4%

Checking Existence of Edge Length Limited Paths II

Depth-First Search Union-Find Graph Theory Design Sorting Heap (Priority Queue)Minimum Spanning Tree

#101

Rank

#1903MediumFrequency: 16.4%

Design Most Recently Used Queue

Array Linked List Divide and Conquer Design Simulation Doubly-Linked List Sqrt Decomposition Treap Splay Tree

#102

Rank

#2352MediumFrequency: 16.4%

Design an ATM Machine

Array Greedy Design

#103

Rank

#2380HardFrequency: 16.4%

Booking Concert Tickets in Groups

Binary Search Design Binary Indexed Tree Segment Tree

#104

Rank

#2396HardFrequency: 16.4%

Design Video Sharing Platform

Hash Table Design Heap (Priority Queue)

#105

Rank

#859MediumFrequency: 14.6%

Design Circular Deque

#106

Rank

#2178MediumFrequency: 14.6%

Walking Robot Simulation II

Design Simulation

#107

Rank

#307MediumFrequency: 10.5%

Range Sum Query - Mutable

Array Divide and Conquer Design Binary Indexed Tree Segment Tree Sqrt Decomposition

#108

Rank

#1512MediumFrequency: 10.3%

Design Underground System

Hash Table String Design

#109

Rank

#352HardFrequency: 8.1%

Data Stream as Disjoint Intervals

Hash Table Binary Search Union-Find Design Data Stream Ordered Set

#110

Rank

#1955MediumFrequency: 8.1%

Seat Reservation Manager

Design Heap (Priority Queue)

#111

Rank

#1470MediumFrequency: 8.1%

Tweet Counts Per Frequency

Hash Table String Binary Search Design Sorting Ordered Set

#112

Rank

#3797MediumFrequency: 8.1%

Design Spreadsheet

Array Hash Table String Design Matrix

#113

Rank

#3827MediumFrequency: 7.3%

Implement Router

Array Hash Table Binary Search Design Queue Ordered Set

#114

Rank

#1294MediumFrequency: 7.3%

Range Frequency Queries

Array Hash Table Binary Search Design Segment Tree

#115

Rank

#1270HardFrequency: 7.2%

Dinner Plate Stacks

Hash Table Stack Design Heap (Priority Queue)

#116

Rank

#4067MediumFrequency: 5.5%

Design Auction System

#117

Rank

#1572MediumFrequency: 5%

Subrectangle Queries

Array Design Matrix

#118

Rank

#1433HardFrequency: 5%

Encrypt and Decrypt Strings

#119

Rank

#1949MediumFrequency: 5%

Implement Trie II (Prefix Tree)

#120

Rank

#4059MediumFrequency: 5%

Design Exam Scores Tracker

Array Binary Search Design Prefix Sum

#121

Rank

#1775EasyFrequency: 5%

Design an Ordered Stream