class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        vector<vector<int>> 
        dp(obstacleGrid.size() , vector<int>(obstacleGrid[0].size() , 0));
        for(int i=0 ; i<obstacleGrid.size() ; i++)
        {
            for(int j=0 ; j<obstacleGrid[0].size() ;j++)
            {
                if(obstacleGrid[i][j] == 1) continue; //遇到障碍物绕开
                if(i==0 && j==0) dp[0][0] = 1; //起始点
                else if(i==0) dp[i][j] =  dp[i][j-1]; //最边行
                else if(j==0) dp[i][j] =  dp[i-1][j]; //最边列
                else dp[i][j] = dp[i-1][j] + dp[i][j-1]; 
            }
        }
        return dp[obstacleGrid.size()-1][obstacleGrid[0].size()-1];
    }
};

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