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.

Array
String
Dictionary
Dynamic Programming
Recursion
Tree

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