3963. Create Grid With Exactly One Path

You are given two integers m and n, representing the number of rows and columns of a grid.

Construct any m x n grid consisting only of the characters '.' and '#', where:

• '.' represents a free cell.
• '#' represents an obstacle cell.

A valid path is a sequence of free cells that:

• Starts at the top-left cell (0, 0).
• Ends at the bottom-right cell (m - 1, n - 1).
• Moves only:
  • Right, from (i, j) to (i, j + 1), or
  • Down, from (i, j) to (i + 1, j).

Return any grid such that there is exactly one valid path from the top-left cell to the bottom-right cell.

Example 1:

Example 2:

Example 3:

Constraints:

• 1 <= m, n <= 25