LeetCode is running the 30-Day LeetCoding Challenge to solve a frequently-asked interview problem.

## Week 1: April 1st–April 7th

- Single Number
- Happy Number
- Maximum Subarray
- Move Zeroes
- Best Time to Buy and Sell Stock II
- Group Anagrams

## Week 2: April 8th–April 14th

- Middle of the Linked List
- Backspace String Compare
- Min Stack
- Diameter of Binary Tree
- Last Stone Weight
- Contiguous Array
- Perform String Shifts

## Week 3: April 15th–April 21st

- Product of Array Except Self
- Valid Parenthesis String
- Number of Islands
- Minimum Path Sum
- Search in Rotated Sorted Array
- Construct Binary Search Tree from Preorder Traversal
- Leftmost Column with at Least a One