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]
]
思路：这道题与Unique Paths思路差不多，就是初始化和运算的过程中要判断obstacleGrid[i][j]为1和0的情况，当obstacleGrid[i][j]为1时，result[i][j]=0,当obstacleGride[i][j]为0时，这个时候情况完全与Unique Paths的情况一样了。

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