## Problem

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 3×3 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.## Analysis

- Similar to Unique Path except that we need to decide whether a position has obstacle or not
- If yes, the number of ways to it is 0