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: The same to Unique Paths, just add obstacle check.

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        if(obstacleGrid.size() <= 0 || obstacleGrid[0].size() <= 0)
            return 0;

        int row = obstacleGrid.size();
        int column = obstacleGrid[0].size();
        vector<int> path_nums(column, 0);
        for(int i = 0; i < row; i ++) {
            int row_idx = row - 1 - i;
            for(int j = 0; j < column; j ++ ) {
                int column_idx = column - 1 - j;
                if(i == 0 && j == 0 && obstacleGrid[row_idx][column_idx] == 1)
                    return 0;
                if(i == 0 && j == 0 && obstacleGrid[row_idx][column_idx] == 0) {
                    path_nums[j] = 1;
                }else {
                    if(obstacleGrid[row_idx][column_idx] == 1) {
                        path_nums[j] = 0;
                    }else {
                        if(j != 0)
                            path_nums[j] += path_nums[j - 1];
                    }
                }
            } 
        }
        return path_nums[column - 1];
    }
};