Rolling Ball Maze Reachability

Rolling Ball Maze

Given a 2D grid representing a maze, where 0 is an empty space and 1 is a wall, a ball starts at coordinate (start_row, start_col) and needs to reach (target_row, target_col).

The ball rolls in one of the four cardinal directions (Up, Down, Left, Right). Once the ball starts rolling in a direction, it continues moving in that straight line until it hits a wall or the boundary of the grid. Only after hitting a wall/boundary can the ball change its direction or stop at the cell immediately before the obstacle.

Implement a function to determine the minimum number of stops required to reach the target. If the target is unreachable, return -1.

Function Signature

def min_stops(maze, start, target) -> int

Constraints

• maze is an M x N grid (1 <= M, N <= 100).
• start and target are valid coordinates (r, c).
• The ball must come to a complete stop before changing direction.

Examples

Example 1: Input: maze = [[0, 0, 1], [0, 0, 0], [0, 1, 0]], start = (0, 0), target = (2, 2) Output: 2 Explanation: Move Right to (0, 1) -> hit wall, then move Down to (2, 2).

Example 2: Input: maze = [[0, 1], [1, 0]], start = (0, 0), target = (1, 1) Output: -1 Explanation: The ball cannot navigate the corners to reach the target.