Unique Paths II

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        
        int rows = obstacleGrid.size();
        int cols = obstacleGrid[0].size();
        int dp[rows][cols];
        
        bool flag = false;
        //Fill  1st row
        for(int i=0;i<cols;++i)
        {
            if(flag || obstacleGrid[0][i]==1)
            {
                flag = true;
                dp[0][i] = 0;
            }
            else
                dp[0][i] = 1;
        }
        
        //Fill 1st column
        flag = false;
        for(int i=0;i<rows;++i)
        {
            if(flag || obstacleGrid[i][0]==1)
            {
                flag = true;
                dp[i][0] = 0;
            }
            else
                dp[i][0] = 1;
        }
        
        for(int i=1;i<rows;++i)
        {
            for(int j=1;j<cols;++j)
            {
                if(obstacleGrid[i][j]==1)
                    dp[i][j] = 0;
                else
                    dp[i][j] = dp[i-1][j] + dp[i][j-1];
            }
        }
        return dp[rows-1][cols-1];
    }
};