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.

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