Unique Paths II

 1 class Solution {
 2 public:
 3     /**
 4      * @param obstacleGrid: A list of lists of integers
 5      * @return: An integer
 6      */ 
 7     int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
 8         // write your code here
 9         
10         int row = obstacleGrid.size();
11         
12         if(row == 0)
13             return 0;
14             
15         int col = obstacleGrid[0].size();
16         
17         
18         vector<vector<int>> f(row, vector<int>(col,0));
19             
20         if(obstacleGrid[0][0] == 1)
21             return 0;
22             
23         f[0][0] = 1;
24         
25         for(int i = 0; i < row; ++i)
26         {
27             for(int j = 0; j < col; ++j)
28             {
29                 if(i == 0 && j == 0)
30                     continue;
31                     
32                 if(obstacleGrid[i][j] == 1)
33                 {
34                     f[i][j] = 0;
35                     continue;
36                 }
37                 
38                 if(i == 0)
39                     f[i][j] = f[i][j-1];
40                 else if(j == 0)
41                     f[i][j] = f[i-1][j];
42                 else
43                     f[i][j] = f[i-1][j] + f[i][j-1];
44             }
45         }
46         
47         return f[row-1][col-1];
48     }
49 };