An algorithm is a sequence of unambiguous steps to do a task. The
challenges below require you to come up with algorithms to solve the
problems.

Reverse String

Kids with the Greatest Number of Candies

Max Consecutive Ones

Third Maximum Number

Largest Number At Least Twice of Others

Check If It Is a Straight Line

Plus One

Find Pivot Index

How Many Numbers Are Smaller Than the Current Number

Replace Elements with Greatest Element on Right Side

Best Time to Buy and Sell Stock

Squares of a Sorted Array

Element Appearing More Than 25% in Sorted Array

Move Zeroes

Remove Duplicates from Sorted Array

Can Place Flowers

Create Target Array in the Given Order

Duplicate Zeros

Monotonic Array

Valid Mountain Array

Best Time to Buy and Sell Stock II

Maximum Subarray

Image Smoother

Shift 2D Grid

Kids with the Greatest Number of Candies

Max Consecutive Ones

Third Maximum Number

Largest Number At Least Twice of Others

Check If It Is a Straight Line

Plus One

Find Pivot Index

How Many Numbers Are Smaller Than the Current Number

Replace Elements with Greatest Element on Right Side

Best Time to Buy and Sell Stock

Squares of a Sorted Array

Element Appearing More Than 25% in Sorted Array

Move Zeroes

Remove Duplicates from Sorted Array

Can Place Flowers

Create Target Array in the Given Order

Duplicate Zeros

Monotonic Array

Valid Mountain Array

Best Time to Buy and Sell Stock II

Maximum Subarray

Image Smoother

Shift 2D Grid

Valid Palindrome

Student Attendance Record I

Reverse Vowels of a String

Reverse Only Letters

Detect Capital

Is Subsequence

Valid Parentheses

Backspace String Compare

Goat Latin

Implement strStr()

Positions of Large Groups

Longest Common Prefix

Long Pressed Name

Valid Palindrome II

Longest Palindromic Substring

Camelcase Matching

Student Attendance Record I

Reverse Vowels of a String

Reverse Only Letters

Detect Capital

Is Subsequence

Valid Parentheses

Backspace String Compare

Goat Latin

Implement strStr()

Positions of Large Groups

Longest Common Prefix

Long Pressed Name

Valid Palindrome II

Longest Palindromic Substring

Camelcase Matching

Contains Duplicate

Single Number

First Unique Character in a String

N-Repeated Element in Size 2N Array

Majority Element

Jewels and Stones

Check If N and Its Double Exist

Find All Numbers Disappeared in an Array

Find Lucky Integer in an Array

Unique Number of Occurrences

Intersection of Two Arrays

Intersection of Two Arrays II

Minimum Index Sum of Two Lists

Find the Difference

Uncommon Words from Two Sentences

Buddy Strings

Isomorphic Strings

Two Sum

Pairs of Songs with Total Durations Divisible by 60

Fair Candy Swap

Set Mismatch

Keyboard Row

Ransom Note

Maximum Number of Balloons

Find the Town Judge

Valid Anagram

Roman to Integer

Find Words That Can Be Formed by Characters

Find Common Characters

Shortest Completing Word

Longest Substring Without Repeating Characters

Group Anagrams

Top K Frequent Elements

Valid Sudoku

Alphabet Board Path

Task Scheduler

Single Number

First Unique Character in a String

N-Repeated Element in Size 2N Array

Majority Element

Jewels and Stones

Check If N and Its Double Exist

Find All Numbers Disappeared in an Array

Find Lucky Integer in an Array

Unique Number of Occurrences

Intersection of Two Arrays

Intersection of Two Arrays II

Minimum Index Sum of Two Lists

Find the Difference

Uncommon Words from Two Sentences

Buddy Strings

Isomorphic Strings

Two Sum

Pairs of Songs with Total Durations Divisible by 60

Fair Candy Swap

Set Mismatch

Keyboard Row

Ransom Note

Maximum Number of Balloons

Find the Town Judge

Valid Anagram

Roman to Integer

Find Words That Can Be Formed by Characters

Find Common Characters

Shortest Completing Word

Longest Substring Without Repeating Characters

Group Anagrams

Top K Frequent Elements

Valid Sudoku

Alphabet Board Path

Task Scheduler

Number of Steps to Reduce a Number to Zero

Power of Three

Add Digits

Happy Number

Last Stone Weight

Count and Say

Pow(x, n)

K-th Symbol in Grammar

Jump Game

Keys and Rooms

Number of Islands

Friend Circles

Word Search

Time Needed to Inform All Employees

Subsets

Combinations

Coin Change

Target Sum

Letter Combinations of a Phone Number

Permutations

Perfect Squares

Maximal Square

Open the Lock

Generate Parentheses

Power of Three

Add Digits

Happy Number

Last Stone Weight

Count and Say

Pow(x, n)

K-th Symbol in Grammar

Jump Game

Keys and Rooms

Number of Islands

Friend Circles

Word Search

Time Needed to Inform All Employees

Subsets

Combinations

Coin Change

Target Sum

Letter Combinations of a Phone Number

Permutations

Perfect Squares

Maximal Square

Open the Lock

Generate Parentheses