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];

    }

};