Description
A robot moves from top-left to bottom-right on a grid. Some cells have obstacles (1). Count unique paths avoiding obstacles. The robot can only move right or down.
Examples
Input:
obstacleGrid = [[0,0,0],[0,1,0],[0,0,0]]Output:
2Explanation:
Two paths around obstacle.
Input:
obstacleGrid = [[0,0],[1,0]]Output:
1Explanation:
Only one path exists: start at (0,0), move right to (0,1), then move down to (1,1). The obstacle at (1,0) blocks the alternative path of moving down first then right.
Input:
obstacleGrid = [[0,1,0,0],[0,0,0,1],[1,0,0,0],[0,0,1,0]]Output:
4Explanation:
Multiple obstacles create a maze-like grid. Starting from top-left (0,0) to bottom-right (3,3), there are 4 unique paths that navigate around the obstacles at positions (0,1), (1,3), (2,0), and (3,2).
Constraints
- •
1 ≤ m, n ≤ 100