[Leetcode] Unique Paths (Java)

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.

计算C(min(m-1,n-1),m+n-2)

public class Solution {    public int uniquePaths(int m, int n) {long res = 1;int high = m+n-2;int low = Math.min(m-1, n-1);int k=0;while(k++<low)res*=high--;for(int i=low;i>0;i--)res/=i;return (int)res;    }}