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(std::vector<std::vector<int> > &obstacleGrid) {
std::vector<std::vector<int>> dp(obstacleGrid.size(),std::vector<int>(obstacleGrid[0].size(),0));
dp[0][0] = obstacleGrid[0][0] ? 0 : 1;
for (int i = 1; i < obstacleGrid.size(); i++)
{
dp[i][0] = obstacleGrid[i][0] ? 0 : dp[i-1][0];
}
for (int i = 1; i < obstacleGrid[0].size(); i++)
{
dp[0][i] = obstacleGrid[0][i] ? 0 : dp[0][i-1];
}
for (int i = 1; i < obstacleGrid.size(); i++)
{
for (int j = 1; j < obstacleGrid[0].size(); j++)
{
dp[i][j] = obstacleGrid[i][j] ? 0 : dp[i-1][j] + dp[i][j-1];
}
}
return dp[obstacleGrid.size()-1][obstacleGrid[0].size()-1];
}
};