[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.

思路：与Unique Paths一样，只是当遇到1时，将dp[i][j]置为0

代码：

class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
int m=obstacleGrid.size(),n=obstacleGrid[0].size();
int dp[m]
;
for(int i=0;i<m;i++){
for(int j=0;j<n;j++){
dp[i][j]=0;
}
}
for(int i=0;i<m;i++){
if(obstacleGrid[i][0]==1) break;
dp[i][0]=1;
}
for(int j=0;j<n;j++){
if(obstacleGrid[0][j]==1) break;
dp[0][j]=1;
}
for(int i=1;i<m;i++){
for(int j=1;j<n;j++){
if(obstacleGrid[i][j]==1) dp[i][j]=0;
else dp[i][j]=dp[i-1][j]+dp[i][j-1];
}
}
return dp[m-1][n-1];
}
};