63. 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.

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        if(obstacleGrid.empty() || obstacleGrid[0].empty()){
            return 0;
        }
        int row = obstacleGrid.size();
        int col = obstacleGrid[0].size();
        
        int dp[row][col];
        
        dp[0][0] = (obstacleGrid[0][0] == 0 ? 1 : 0);
        
        for(int i = 1; i < row; i++){
            dp[i][0] = ((dp[i-1][0] == 1 && obstacleGrid[i][0] == 0)? 1 : 0);
        }
        
        for(int j = 1; j < col; j++){
            dp[0][j] = ((dp[0][j-1] == 1 && obstacleGrid[0][j] == 0)? 1: 0);
        }
        
        for(int i = 1 ; i < row; i++){
            for(int j = 1 ; j < col;j++){
                if(obstacleGrid[i][j] == 1){
                    dp[i][j] = 0;
                }else{
                    dp[i][j] = dp[i-1][j]+dp[i][j-1];
                }
            }
        }
        
        return dp[row-1][col-1];
    }
};