LeetCode Day 6

 I tackled my first leetcode hard problem. Man those are not jokes. Although its not a "hard" difficulty problem on leetcode. To me, it was soooo harddd. It was a leetcode problem called Valid Sodoku. All about matrices.

My solution:

My notes:

- Finished valid Sudoku which was a borderline hard problem

- I had all the logic correct, and I came up with a pretty good solution. There is always a trick to each of the leetcodes. Even when you think they couldn't have possibly considered the solution that you are typing THEY HAVE!. Leet codes are well designed

- Also if you use {}, python assumes that its a dictionary, just use set() instead