You are given an m x n
integer array grid
. There is a robot initially located at the top-left corner (i.e., grid[0][0]
). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]
). The robot can only move either down or right at any point in time.
An obstacle and space are marked as 1
or 0
respectively in grid
. A path that the robot takes cannot include any square that is an obstacle.
Return the number of possible unique paths that the robot can take to reach the bottom-right corner.
The testcases are generated so that the answer will be less than or equal to 2 * 109
.
Example 1:
**Input:** obstacleGrid = \[\[0,0,0\],\[0,1,0\],\[0,0,0\]\]
**Output:** 2
**Explanation:** There is one obstacle in the middle of the 3x3 grid above.
There are two ways to reach the bottom-right corner:
1. Right -> Right -> Down -> Down
2. Down -> Down -> Right -> Right
Example 2:
**Input:** obstacleGrid = \[\[0,1\],\[0,0\]\]
**Output:** 1
Constraints:
m == obstacleGrid.length
n == obstacleGrid[i].length
1 <= m, n <= 100
obstacleGrid[i][j]
is0
or1
.