题目：
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?
解法一：自己写的，比较诡异
1 public int uniquePaths(int m, int n) 2 { 3 int [][] grids = new int [m+1][n+1]; 4 grids[m][n-1]=1; 5 for (int i=m-1;i>=0;i--) 6 { 7 for (int j=n-1;j>=0;j--) 8 { 9 grids[i][j]=grids[i+1][j]+grids[i][j+1]; 10 11 12 } 13 } 14 return grids[0][0]; 15 }
解法二：九章算法，好理解
1 public class Solution { 2 public int uniquePaths(int m, int n) { 3 if (m == 0 || n == 0) { 4 return 0; 5 } 6 7 int[][] sum = new int[m][n]; 8 for (int i = 0; i < m; i++) { 9 sum[i][0] = 1; 10 } 11 for (int i = 0; i < n; i++) { 12 sum[0][i] = 1; 13 } 14 for (int i = 1; i < m; i++) { 15 for (int j = 1; j < n; j++) { 16 sum[i][j] = sum[i - 1][j] + sum[i][j - 1]; 17 } 18 } 19 return sum[m - 1][n - 1]; 20 } 21 }reference：http://www.jiuzhang.com/solutions/unique-paths/
转载于:https://www.cnblogs.com/hygeia/p/4831696.html
