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) {
unsigned m = obstacleGrid.size();
unsigned n = obstacleGrid[0].size();

if (m == 0 || n == 0)
return 0;

vector<vector<int> > array(m, vector<int>(n, 1));

for (int i = 0; i < m; ++i) {
if (obstacleGrid[i][0] == 1) {
for (int j = i; j < m; ++j)
array[j][0] = 0;
break;
}
}

for (int i = 0; i < n; ++i) {
if (obstacleGrid[0][i] == 1) {
for (int j = i; j < n; ++j)
array[0][j] = 0;
break;
}
}

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

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