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

Largest Number At Least Twice of Others

Third Maximum Number

Plus One

Check If It Is a Straight Line

How Many Numbers Are Smaller Than the Current Number

Replace Elements with Greatest Element on Right Side

Find Pivot Index

Best Time to Buy and Sell Stock

Can Place Flowers

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

Largest Number At Least Twice of Others

Third Maximum Number

Plus One

Check If It Is a Straight Line

How Many Numbers Are Smaller Than the Current Number

Replace Elements with Greatest Element on Right Side

Find Pivot Index

Best Time to Buy and Sell Stock

Can Place Flowers

Monotonic Array

Valid Mountain Array

Best Time to Buy and Sell Stock II

Maximum Subarray

Image Smoother

Shift 2D Grid

Contains Duplicate

First Unique Character in a String

Majority Element

Jewels and Stones

Find Lucky Integer in an Array

Check If N and Its Double Exist

Two Sum

Intersection of Two Arrays

Minimum Index Sum of Two Lists

Find the Difference

Uncommon Words from Two Sentences

Isomorphic Strings

Pairs of Songs with Total Durations Divisible by 60

Fair Candy Swap

Set Mismatch

Keyboard Row

Ransom Note

Maximum Number of Balloons

Roman to Integer

Find the Town Judge

Valid Anagram

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

First Unique Character in a String

Majority Element

Jewels and Stones

Find Lucky Integer in an Array

Check If N and Its Double Exist

Two Sum

Intersection of Two Arrays

Minimum Index Sum of Two Lists

Find the Difference

Uncommon Words from Two Sentences

Isomorphic Strings

Pairs of Songs with Total Durations Divisible by 60

Fair Candy Swap

Set Mismatch

Keyboard Row

Ransom Note

Maximum Number of Balloons

Roman to Integer

Find the Town Judge

Valid Anagram

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

Number of Provinces

Word Search

Time Needed to Inform All Employees

Subsets

Combinations

Rotting Oranges

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

Number of Provinces

Word Search

Time Needed to Inform All Employees

Subsets

Combinations

Rotting Oranges

Target Sum

Letter Combinations of a Phone Number

Permutations

Perfect Squares

Maximal Square

Open the Lock

Generate Parentheses