LeetCode Unique Paths

题目如下：

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.

这题其实非常简单，放着就是为了描述动态规划算法。看了代码就明白了。

 1 int uniquePaths(int m, int n) {
 2     int *A;
 3     A=(int*)malloc(sizeof(int)*m*n);
 4     int a,b;
 5     for(a=m-1,b=0;b<n;b++){
 6         A[a*n+b]=1;
 7     }
 8     for(b=n-1,a=0;a<m;a++){
 9         A[a*n+b]=1;
10     }
11     for(a=m-2;a>=0;a--){
12         for(b=n-2;b>=0;b--){
13             A[a*n+b]=A[(a+1)*n+b]+A[a*n+b+1];
14         }
15     }
16     return A[0];
17 }

类似的题Minimum Path Sum也可以通过这个方法解决。

LeetCode Unique Paths

原文：http://www.cnblogs.com/asawanggaa/p/4403573.html