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

.

Note: m and n will
be at most 100.

class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
int m = obstacleGrid.size();
if (m == 0)
return 0;
int n = obstacleGrid[0].size();
if (n == 0)
return 0;

if(1 == obstacleGrid[0][0] || 1 == obstacleGrid[m - 1][n - 1])
return 0;

vector< vector<int> > path(m, vector<int>(n));
for (int i = 0; i < m; ++i)
{
if (obstacleGrid[i][0] == 0)
path[i][0] = 1;
else
{
do
{
path[i++][0] = 0;
}while(i < m);
}
}

for (int j = 0; j < n; ++j)
{
if (obstacleGrid[0][j] == 0)
{
path[0][j] = 1;
}
else
{
do
{
path[0][j++] = 0;
}while(j < n);
}
}

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

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