This problem was asked by Slack.
You are given an N by M matrix of 0s and 1s. Starting from the top left corner, how many ways are there to reach the bottom right corner?
You can only move right and down. 0 represents an empty space while 1 represents a wall you cannot walk through.
For example, given the following matrix:
[[0, 0, 1],
[0, 0, 1],
[1, 0, 0]]
Return two, as there are only two ways to get to the bottom right:
- Right, down, down, right
- Down, right, down, right
The top left corner and bottom right corner will always be 0.