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.
解题思路：
本题如果使用上题中的解法一，将会非常复杂，因此我们修改解法二即可，JAVA实现如下：
public int uniquePathsWithObstacles(int[][] obstacleGrid) {
int[] v = new int[obstacleGrid[0].length];
for (int i = 0; i < v.length; i++)
if (obstacleGrid[0][i] == 0)
v[i] = 1;
else
break;
for (int i = 1; i < obstacleGrid.length; i++) {
if (obstacleGrid[i][0] == 1)
v[0] = 0;
for (int j = 1; j < v.length; j++)
if (obstacleGrid[i][j] == 1)
v[j] = 0;
else
v[j] += v[j - 1];
}
return v[v.length - 1];
}