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.

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