Rotate a 3×3 digit grid by 180°

Problem Statement

You are given a 3x3 grid represented as a list of strings, where each string contains three digits (0-9). Your task is to rotate the entire grid 180 degrees.

A 180-degree rotation is equivalent to reversing the order of the rows and then reversing the order of the characters within each row. Alternatively, the character at coordinate (r, c) (0-indexed) moves to (2-r, 2-c).

Function Signature

def rotate_grid_180(grid: list[str]) -> list[str]:
    pass

Constraints

• grid will always be a list of 3 strings.
• Each string in grid will always contain exactly 3 digits.

Examples

Example 1: Input:

[
  "123",
  "456",
  "789"
]

Output:

[
  "987",
  "654",
  "321"
]

Explanation: The element at (0,0) '1' moves to (2,2). The element at (0,1) '2' moves to (2,1), and so on.

Example 2: Input:

[
  "000",
  "111",
  "222"
]

Output:

[
  "222",
  "111",
  "000"
]

Edge Cases

• Grids with all identical digits.
• Grids where the center element is the same after rotation (e.g., '5' in a 3x3 grid).