unique-paths

1、链接：这里写链接内容

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?Above is a 3 x 7 grid. How many possible unique paths are there?Note: m and n will be at most 100.

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