Where Will the Ball Fall
You have a 2-D grid of size m x n representing a box, and you have n balls. The box is open on the top and bottom sides.
Each cell in the box has a diagonal board spanning two corners of the cell that can redirect a ball to the right or to the left.
- A board that redirects the ball to the right spans the top-left corner to the bottom-right corner and is represented in the grid as
1. - A board that redirects the ball to the left spans the top-right corner to the bottom-left corner and is represented in the grid as
-1.
We drop one ball at the top of each column of the box. Each ball can get stuck in the box or fall out of the bottom. A ball gets stuck if it hits a "V" shaped pattern between two boards or if a board redirects the ball into either wall of the box.
Return an array answer of size n where answer[i] is the column that the ball falls out of at the bottom after dropping the ball from the i^th column at the top, or -1 if the ball gets stuck in the box.
Example 1
1 1 1 -1 -1 1 1 1 -1 -1 -1 -1 -1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1
Input
grid = [[1,1,1,-1,-1],[1,1,1,-1,-1],[-1,-1,-1,1,1],[1,1,1,1,-1],[-1,-1,-1,-1,-1]]Output
[1,-1,-1,-1,-1]Ball b0 falls out at column 1, while balls b1 through b4 get stuck in the box.
Example 2
-1
Input
grid = [[-1]]Output
[-1]The ball gets stuck against the left wall.
Constraints
- m == grid.length
- n == grid[i].length
- 1 <= m, n <= 100
- grid[i][j] is 1 or -1.