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.
Note: m and n will be at most 100.
与上题差别不大，只需要判断有障碍置零即可。
对于首行首列，第一个障碍及之后的路径数均为0
class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
if(obstacleGrid.empty())
return ;
int m = obstacleGrid.size();
if(obstacleGrid[].empty())
return ;
int n = obstacleGrid[].size();
vector<vector<int> > path(m, vector<int>(n, ));
for(int i = ; i < m; i ++)
{
if(obstacleGrid[i][] != )
path[i][] = ;
else
break;
}
for(int i = ; i < n; i ++)
{
if(obstacleGrid[][i] != )
path[][i] = ;
else
break;
}
for(int i = ; i < m; i ++)
{
for(int j = ; j < n; j ++)
{
if(obstacleGrid[i][j] == )
path[i][j] = ;
else
path[i][j] = path[i-][j] + path[i][j-];
}
}
return path[m-][n-];
}
};