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?

public class Solution {
    public int uniquePaths(int m, int n) {
        if(m==0||n==0){
            return 0;
        }
        int paths[] = new int [n];
        paths[0] = 1;
        for(int i = 0; i<m; i++){
            for(int j = 1; j<n; j++){
                paths[j] = paths[j-1] + paths[j];
            }
        }
        return paths[n-1];
    }
}