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?

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

        return map[m-1][n-1];
    }
}