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.
\n\nThe testcases are generated so that the answer will be less than or equal to 2 * 109.
\n
Example 1:
\n![\"\"](\"https://assets.leetcode.com/uploads/2020/11/04/robot1.jpg\")
\n\nInput: obstacleGrid = [[0,0,0],[0,1,0],[0,0,0]]\nOutput: 2\nExplanation: There is one obstacle in the middle of the 3x3 grid above.\nThere are two ways to reach the bottom-right corner:\n1. Right -> Right -> Down -> Down\n2. Down -> Down -> Right -> Right\n\n\n
Example 2:
\n![\"\"](\"https://assets.leetcode.com/uploads/2020/11/04/robot2.jpg\")
\n\nInput: obstacleGrid = [[0,1],[0,0]]\nOutput: 1\n\n\n
\n
Constraints:
\n\nm == obstacleGrid.lengthn == obstacleGrid[i].length1 <= m, n <= 100obstacleGrid[i][j] is 0 or 1.Compiled with clang 11 using the latest C++ 20 standard.
Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
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