leetcode62 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.

 1 class Solution {
 2 public:
 3     int uniquePaths(int m, int n) {
 4 /*      if(n==1)
 5             return 1;
 6         int ans=0;
 7         vector<int> jlist(n-1,1);
 8         for(int i=1;i<m;i++)
 9         {
10             for(int j=0;j<n-1;j++)
11             {
12                 if(j==0)
13                     jlist[j]++;
14                 else
15                     jlist[j]+=jlist[j-1];
16             }
17         }
18         return jlist[n-2];*/
19         int ans=0;
20         vector<int> jlist(n,1);
21         for(int i=1;i<m;i++)
22         {
23             for(int j=1;j<n;j++)
24                 jlist[j]+=jlist[j-1];
25         }
26         return jlist[n-1];
27     }
28 };
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posted @ 2016-01-06 15:46  西小贝  阅读(158)  评论(0)    收藏  举报