leetcode-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]
]

The total number of unique paths is 2.

思路：跟Unique Paths 类似，依然动态规划解决，不同点在于障碍处处理的细节。

代码：

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 *map=new int[n];
for(int i=n-1; i>=0; --i)
{
if(obstacleGrid[m-1][i]==1)
{
map[i]=0;
}
else
{
if(i<n-1 && map[i+1]==0)
{
map[i]=0;
}
else
{
map[i]=1;
}
}

}
for(int i=m-2; i>=0; --i)
{
for(int j=n-1; j>=0; --j)
{
if(obstacleGrid[i][j]==1)
{
map[j]=0;
}
else
{
   if(j<n-1)
{
map[j]+=map[j+1];
}
}

}
}
return map[0];
    }