Unique Paths II

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