(java)leetcode-62:Unique Paths

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.

解体思路：

这道题就只是一点小思路，第i行j列的路径数量（记为p(i,j)），p(i,j) = p(i,j-1) + p(i-1,j)，其他的就没了。

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