Unique Paths II

Q: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.

A: 动态规划

    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int m = obstacleGrid.size();
        if(m==0)
            return 0;
        int n = obstacleGrid[0].size();
        
        if(obstacleGrid[m-1][n-1]==1||obstacleGrid[0][0]==1)
            return 0;
        
        vector<vector<int> > count;
        
        int i,j;
        for(i=0;i<m;i++)
            count.push_back(vector<int>(n));
        
        count[0][0] = 1;
            
        for(i=1;i<m;i++)
            count[i][0] = ((obstacleGrid[i][0]==1||count[i-1][0]==0)?0:1);
        for(j=1;j<n;j++)
            count[0][j] = ((obstacleGrid[0][j]==1||count[0][j-1]==0)?0:1);
            
        for(i=1;i<m;i++)
            for(j=1;j<n;j++)
                count[i][j] = ((obstacleGrid[i][j]==1)?0:count[i-1][j]+count[i][j-1]);
        
        return count[m-1][n-1];
        
    }