(Java)LeetCode-62. 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?

Above is a 3 x 7 grid. How many possible unique paths are there?

Note: m and n will be at most 100.

这一题是数学题啊。。搞清楚之后编程是木有难度的~由于只能向右或向下移动，所以达到一个点的路径数目等与到达这个点上面和左边点的路径数之和，而最上边和最左边两条边的路径数都是1  代码如下：

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