Unique Paths II.cpp

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        
      
        int m = obstacleGrid.size(), n = obstacleGrid[0].size();
        
        vector<vector<int>> dp(m, vector<int>(n, 0));
        dp[0][0] = !obstacleGrid[0][0];
    
        
        for(int i=1; i<n; i++)
        {
            if(obstacleGrid[0][i] == 1)
                dp[0][i] = 0;
            else
                dp[0][i] = dp[0][i-1];
        }    
        
        for(int i=1; i<m; i++)
        {
            if(obstacleGrid[i][0] == 1)
                dp[i][0] = 0;
            else
                dp[i][0] = dp[i-1][0];
        }    
        
        for(int i=1; i<m; i++)
        {
            for(int j=1; j<n; j++)
            {
                
                    if(obstacleGrid[i][j] == 1)
                        dp[i][j] = 0;
                    else
                    
                    dp[i][j] = dp[i-1][j] + dp[i][j-1];
        
                
            }
        }
        return dp[m-1][n-1];
      
        
    }
};