Describe an advanced data structure : From Painfully Slow to Optimal: The Maximum Sum Subarray

The video tutorial explains how to solve the maximum sum subarray problem using different approaches. It starts with a brute force method using nested loops, which has a time complexity of O(n^3). The tutorial then optimizes this to O(n^2) by reducing unnecessary calculations. Finally, it introduces Kadane's Algorithm, which efficiently solves the problem in O(n) time. The video also emphasizes the importance of testing implementations to ensure correctness.

What choices do we have when encountering a negative number in the subarray?

Explain the formula used to calculate the current sum in the final implementation.

Why is it important to write tests for the code implementation?