1. Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands.
2. How would you implement a worker pool in Go?
3. Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.
4. What are some test cases for an ATM?
5. Do you have knowledge about inside sales or lending?