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 < 1)
{
return 0;
}
int n = obstacleGrid[0].size();
if (n < 1)
{
return 0;
}

int buf[m]
;
bool obstacleFound = false;
for (int i = 0; i < m; i++)
{
if (!obstacleFound && obstacleGrid[i][0] == 0)
{
buf[i][0] = 1;
}
else
{
buf[i][0] = 0;
obstacleFound = true;
}
}

obstacleFound = false;
for (int i = 0; i < n; i++)
{
if (!obstacleFound && obstacleGrid[0][i] == 0)
{
buf[0][i] = 1;
}
else
{
buf[0][i] = 0;
obstacleFound = true;
}
}

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

return buf[m-1][n-1];
}
};