Solutions & Explanations

Browse 4,029+ detailed solutions with multiple approaches, code in Python, Java, C++ and more.

4,029 Solutions961 Easy2102 Medium966 Hard

Title	Difficulty	Acceptance	Topics	Solution
1. Two Sum	Easy	57.8%	Array Hash Table	Read
9. Palindrome Number	Easy	61.0%	Math	Read
13. Roman to Integer	Easy	67.0%	Hash Table Math+1	Read
14. Longest Common Prefix	Easy	48.0%	String Trie	Read
20. Valid Parentheses	Easy	44.5%	Stack String	Read
21. Merge Two Sorted Lists	Easy	68.7%	Linked List Recursion	Read
26. Remove Duplicates from Sorted Array	Easy	63.7%	Array Two Pointers	Read
27. Remove Element	Easy	62.2%	Array Two Pointers	Read
28. Find the Index of the First Occurrence in a String	Easy	47.0%	String String Matching+1	Read
35. Search Insert Position	Easy	52.1%	Array Binary Search	Read
58. Length of Last Word	Easy	59.7%	String	Read
66. Plus One	Easy	50.3%	Array Math	Read
67. Add Binary	Easy	58.4%	Bit Manipulation Math+2	Read
69. Sqrt(x)	Easy	42.2%	Binary Search Math	Read
70. Climbing Stairs	Easy	54.0%	Dynamic Programming Math+1	Read
83. Remove Duplicates from Sorted List	Easy	57.6%	Linked List	Read
88. Merge Sorted Array	Easy	55.7%	Array Sorting+1	Read
94. Binary Tree Inorder Traversal	Easy	80.4%	Binary Tree Depth-First Search+2	Read
100. Same Tree	Easy	68.0%	Binary Tree Breadth-First Search+2	Read
101. Symmetric Tree	Easy	61.5%	Binary Tree Breadth-First Search+2	Read
104. Maximum Depth of Binary Tree	Easy	78.6%	Binary Tree Breadth-First Search+2	Read
108. Convert Sorted Array to Binary Search Tree	Easy	75.9%	Array Binary Search Tree+3	Read
110. Balanced Binary Tree	Easy	59.2%	Binary Tree Depth-First Search+1	Read
111. Minimum Depth of Binary Tree	Easy	53.7%	Binary Tree Breadth-First Search+2	Read
112. Path Sum	Easy	55.2%	Binary Tree Breadth-First Search+2	Read
118. Pascal's Triangle	Easy	79.4%	Array Dynamic Programming	Read
119. Pascal's Triangle II	Easy	67.8%	Array Dynamic Programming	Read
121. Best Time to Buy and Sell Stock	Easy	57.1%	Array Dynamic Programming	Read
125. Valid Palindrome	Easy	54.2%	String Two Pointers	Read
136. Single Number	Easy	78.1%	Array Bit Manipulation	Read
141. Linked List Cycle	Easy	54.6%	Hash Table Linked List+1	Read
144. Binary Tree Preorder Traversal	Easy	76.6%	Binary Tree Depth-First Search+2	Read
145. Binary Tree Postorder Traversal	Easy	79.0%	Binary Tree Depth-First Search+2	Read
157. Read N Characters Given Read4	Easy	42.5%	Array Interactive+1	Read
160. Intersection of Two Linked Lists	Easy	64.6%	Hash Table Linked List+1	Read
163. Missing Ranges	Easy	35.5%	Array	Read
168. Excel Sheet Column Title	Easy	47.3%	Math String	Read
169. Majority Element	Easy	66.2%	Array Counting+3	Read
170. Two Sum III - Data structure design	Easy	39.1%	Array Data Stream+3	Read
171. Excel Sheet Column Number	Easy	68.0%	Math String	Read
175. Combine Two Tables	Easy	77.1%	Database	Read
181. Employees Earning More Than Their Managers	Easy	70.6%	Database	Read
182. Duplicate Emails	Easy	71.8%	Database	Read
183. Customers Who Never Order	Easy	69.9%	Database	Read
190. Reverse Bits	Easy	69.2%	Bit Manipulation Divide and Conquer	Read
191. Number of 1 Bits	Easy	77.1%	Bit Manipulation Divide and Conquer	Read
193. Valid Phone Numbers	Easy	26.6%	Shell	Read
195. Tenth Line	Easy	33.8%	Shell	Read
196. Delete Duplicate Emails	Easy	63.4%	Database	Read
197. Rising Temperature	Easy	49.3%	Database	Read

#1Easy

Two Sum

ArrayHash Table

Acceptance: 57.8%

#9Easy

Palindrome Number

Math

Acceptance: 61.0%

#13Easy

Roman to Integer

Hash TableMathString

Acceptance: 67.0%

#14Easy

Longest Common Prefix

StringTrie

Acceptance: 48.0%

#20Easy

Valid Parentheses

StackString

Acceptance: 44.5%

#21Easy

Merge Two Sorted Lists

Linked ListRecursion

Acceptance: 68.7%

#26Easy

Remove Duplicates from Sorted Array

ArrayTwo Pointers

Acceptance: 63.7%

#27Easy

Remove Element

ArrayTwo Pointers

Acceptance: 62.2%

#28Easy

Find the Index of the First Occurrence in a String

StringString MatchingTwo Pointers

Acceptance: 47.0%

#35Easy

Search Insert Position

ArrayBinary Search

Acceptance: 52.1%

#58Easy

Length of Last Word

String

Acceptance: 59.7%

#66Easy

Plus One

ArrayMath

Acceptance: 50.3%

#67Easy

Add Binary

Bit ManipulationMathSimulation+1

Acceptance: 58.4%

#69Easy

Sqrt(x)

Binary SearchMath

Acceptance: 42.2%

#70Easy

Climbing Stairs

Dynamic ProgrammingMathMemoization

Acceptance: 54.0%

#83Easy

Remove Duplicates from Sorted List

Linked List

Acceptance: 57.6%

#88Easy

Merge Sorted Array

ArraySortingTwo Pointers

Acceptance: 55.7%

#94Easy

Binary Tree Inorder Traversal

Binary TreeDepth-First SearchStack+1

Acceptance: 80.4%

#100Easy

Same Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 68.0%

#101Easy

Symmetric Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 61.5%

#104Easy

Maximum Depth of Binary Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 78.6%

#108Easy

Convert Sorted Array to Binary Search Tree

ArrayBinary Search TreeBinary Tree+2

Acceptance: 75.9%

#110Easy

Balanced Binary Tree

Binary TreeDepth-First SearchTree

Acceptance: 59.2%

#111Easy

Minimum Depth of Binary Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 53.7%

#112Easy

Path Sum

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 55.2%

#118Easy

Pascal's Triangle

ArrayDynamic Programming

Acceptance: 79.4%

#119Easy

Pascal's Triangle II

ArrayDynamic Programming

Acceptance: 67.8%

#121Easy

Best Time to Buy and Sell Stock

ArrayDynamic Programming

Acceptance: 57.1%

#125Easy

Valid Palindrome

StringTwo Pointers

Acceptance: 54.2%

#136Easy

Single Number

ArrayBit Manipulation

Acceptance: 78.1%

#141Easy

Linked List Cycle

Hash TableLinked ListTwo Pointers

Acceptance: 54.6%

#144Easy

Binary Tree Preorder Traversal

Binary TreeDepth-First SearchStack+1

Acceptance: 76.6%

#145Easy

Binary Tree Postorder Traversal

Binary TreeDepth-First SearchStack+1

Acceptance: 79.0%

#157Easy

Read N Characters Given Read4

ArrayInteractiveSimulation

Acceptance: 42.5%

#160Easy

Intersection of Two Linked Lists

Hash TableLinked ListTwo Pointers

Acceptance: 64.6%

#163Easy

Missing Ranges

Array

Acceptance: 35.5%

#168Easy

Excel Sheet Column Title

MathString

Acceptance: 47.3%

#169Easy

Majority Element

ArrayCountingDivide and Conquer+2

Acceptance: 66.2%

#170Easy

Two Sum III - Data structure design

ArrayData StreamDesign+2

Acceptance: 39.1%

#171Easy

Excel Sheet Column Number

MathString

Acceptance: 68.0%

#175Easy

Combine Two Tables

Database

Acceptance: 77.1%

#181Easy

Employees Earning More Than Their Managers

Database

Acceptance: 70.6%

#182Easy

Duplicate Emails

Database

Acceptance: 71.8%

#183Easy

Customers Who Never Order

Database

Acceptance: 69.9%

#190Easy

Reverse Bits

Bit ManipulationDivide and Conquer

Acceptance: 69.2%

#191Easy

Number of 1 Bits

Bit ManipulationDivide and Conquer

Acceptance: 77.1%

#193Easy

Valid Phone Numbers

Shell

Acceptance: 26.6%

#195Easy

Tenth Line

Shell

Acceptance: 33.8%

#196Easy

Delete Duplicate Emails

Database

Acceptance: 63.4%

#197Easy

Rising Temperature

Database

Acceptance: 49.3%

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