Leetcode 63 Unique Paths II

Follow up for "Unique Paths":

Now consider if some obstacles are added to the grids. How many unique paths would there be?

An obstacle and empty space is marked as 

1

 and 

0

 respectively
in the grid.

For example,

There is one obstacle in the middle of a 3x3 grid as illustrated below.

[
[0,0,0],
[0,1,0],
[0,0,0]
]

The total number of unique paths is 

2

.

Note: m and n will be at most 100.
和62题一致，在转移的时候加一个特判条件，只有是空地的时候才转移。
http://blog.csdn.net/accepthjp/article/details/52585069

class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
if(obstacleGrid.size()==0) return 0;
vector<int> row(obstacleGrid[0].size()+1,0);
vector<vector<int>> dp(obstacleGrid.size()+1,row);
dp[0][1]=1;
for(int i=1;i<=obstacleGrid.size();i++)
for(int j=1;j<=obstacleGrid[0].size();j++)
if(obstacleGrid[i-1][j-1]==0)
dp[i][j]=dp[i-1][j]+dp[i][j-1];
return dp[obstacleGrid.size()][obstacleGrid[0].size()];
}
};