[leetcode]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

        if(obstacleGrid.empty()) return 0;

        int m = obstacleGrid.size();

        int n = obstacleGrid[0].size();

        

        vector<vector<int>> f(m, vector<int>(n, 0));

        

        for(int j = 0; j < n; j++){

            if(obstacleGrid[0][j] == 1){

                break;

            }else{

                f[0][j] = 1;

            }

        }

        

        for(int i = 0; i < m; i++){

            if(obstacleGrid[i][0] == 1){

                break;

            }else{

                f[i][0] = 1;

            }

        }

        

        for(int i = 1; i < m; i++){

            for(int j = 1; j < n; j++){

                if(obstacleGrid[i][j] == 1){

                    f[i][j] = 0;

                }else{

                    f[i][j] = f[i-1][j] + f[i][j-1];

                }  

            }

        }

        return f[m-1][n-1];

    }

};