What most online programming courses don’t teach you

If you’re reading this, you probably have already done an interview before, or at least intend to do one in the future for a job.

This week I stumbled across someone trying to solve a common LeetCode problem: the Sudoku Solver. If you never saw this question, I’ll summarize it:

You are given a 9x9 nested array representing a Sudoku board. Your 
task is to create a function to solve it by filling the missing 
numbers and return the solved board.