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) {
if(obstacleGrid.empty())return 0;
int m=obstacleGrid.size();
int n=obstacleGrid[0].size();
vector<vector<int>> map(m+1);
for(int i=0;i<=m;i++)map[i].assign(n+1,0);
map[1][0]=1;
for(int i=0;i<m;i++){
for(int j=0;j<n;j++){
if(obstacleGrid[i][j])continue;
map[i+1][j+1]=map[i][j+1]+map[i+1][j];
}
}
return map[m][n];
}
};原文：http://blog.csdn.net/starcuan/article/details/18847827