LeetCode 63 - Unique Paths II

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.

My Code

class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
int m = obstacleGrid.size(), n = obstacleGrid[0].size();
vector<vector<int> > grid(m, vector<int>(n, 0));

int ii = 0;
for (; ii < m && obstacleGrid[ii][0] == 0; ii++)
grid[ii][0] = 1;
int jj = 0;
for (; jj < n && obstacleGrid[0][jj] == 0; jj++)
grid[0][jj] = 1;

for (int i = 1; i < m; i++)
for (int j = 1; j < n; j++)
{
if (obstacleGrid[i][j] == 1)
continue;

grid[i][j] = grid[i-1][j] + grid[i][j-1];
}

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

Runtime: 6 ms