https://leetcode.com/problems/unique-paths/
A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).
The robot can only move either down or right at any point in time.
The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).
How many possible unique paths are there?
Example 1:
Input: m = 3, n = 7 Output: 28
Example 2:
Input: m = 3, n = 2 Output: 3 Explanation: From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
- Right -> Down -> Down
- Down -> Down -> Right
- Down -> Right -> Down Example 3:
Input: m = 7, n = 3 Output: 28 Example 4:
Input: m = 3, n = 3 Output: 6
Constraints:
1 <= m, n <= 100 It's guaranteed that the answer will be less than or equal to 2 * 10^9.