Java for LeetCode 062 Unique Paths

標籤：

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?

解題思路一：

BigInteger，JAVA實現如下：

import java.math.BigInteger;public class Solution {public int uniquePaths(int m, int n) {if (n > m) {int temp = n;n = m;m = temp;}return Amn(m + n - 2, n - 1).divide(factorial(n - 1)).intValue();}static BigInteger Amn(int m, int n) {if (n == 0)return BigInteger.valueOf(1);if (n == 1)return BigInteger.valueOf(m);elsereturn Amn(m - 1, n - 1).multiply(BigInteger.valueOf(m));}static BigInteger factorial(int n) {if (n == 1 || n == 0)return BigInteger.valueOf(1);elsereturn factorial(n - 1).multiply(BigInteger.valueOf(n));}}

 

Java for LeetCode 062 Unique Paths