Leetcode133: 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

.

class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
int m = obstacleGrid.size();
if(m == 0)
return 0;
int n = obstacleGrid[0].size();
vector<vector<int>> f(m, vector<int>(n));
//初始化行
int i;
for(i = 0; i < m; i++)
{
if(obstacleGrid[i][0] == 1)
break;
else
f[i][0] = 1;
}
for(; i< m; i++)
{
f[i][0] == 0;
}
//初始化列
for(i = 0; i < n; i++)
{
if(obstacleGrid[0][i] == 1)
break;
else
f[0][i] = 1;
}
for(; i< n; i++)
{
f[0][i] == 0;
}
//递推
for(i = 1; i < m; i++)
{
for(int j = 1; j < n; j++)
{
f[i][j] = obstacleGrid[i][j] == 1 ? 0:f[i-1][j] + f[i][j-1];
}
}
return f[m-1][n-1];
}
};