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

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