Unique Paths II [Leetcode]

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.

Solution: dynamic programming; similar to the Unique Path I; the only thing you need to take care of is "obstacle" (Lines 11-14).

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(obstacleGrid.empty() || obstacleGrid[0].empty()) return 0;
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector<vector<int> > paths(m, vector<int>(n, 0));
        for(int i=m-1; i>=0; i--){
            for(int j=n-1; j>=0; j--){
                if(obstacleGrid[i][j]==1){
                    paths[i][j] = 0;
                    continue;
                }
                if(i==m-1){
                    paths[i][j] = (j==n-1?1:paths[i][j+1]);
                }
                else{
                    paths[i][j] = paths[i+1][j] + (j==n-1?0:paths[i][j+1]);
                }
            }
        }
        return paths[0][0];
    }
};