Unique Paths II DP

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.

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