[LeetCode] 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();
        if(0 == m) return 0;
        int n = obstacleGrid[0].size();
        if(0 == n) return 0;
        int paths[m][n];
        paths[0][0] = obstacleGrid[0][0] == 1?0:1;
        for(int i=1;i<m;i++) 
        {
            if(obstacleGrid[i][0] == 1)paths[i][0] = 0;
            else paths[i][0] = paths[i-1][0];
        }
        for(int i=1;i<n;i++) 
        {
            if(obstacleGrid[0][i] == 1)paths[0][i] = 0;
            else paths[0][i] = paths[0][i-1];
        }        
        for(int i=1;i<m;i++)
        {
            for(int j=1;j<n;j++)
            {
                if(obstacleGrid[i][j] == 1) paths[i][j]=0;
                else paths[i][j] = 
                        paths[i-1][j] + paths[i][j-1];
            }
        }
        return paths[m-1][n-1];
    }
};