Count same-color squares in a character grid

You are given a 2D grid (matrix) of characters. Each character represents a color: cells with the same character are considered the same color.

Formally:

• The grid has m rows and n columns.
• grid[i][j] is an alphabetic character (e.g., 'a' – 'z' or 'A' – 'Z' ).

A square in this grid is defined as a contiguous k × k submatrix aligned with the grid axes, for some integer k ≥ 1.

A square is monochromatic if all of its cells contain the same character (i.e., the same color).

Task:

• Count and return the total number of monochromatic squares in the grid.
• Count all sizes of squares (1×1, 2×2, ..., up to the largest possible that fits in the grid).

Example (just for clarity, not necessarily exhaustive):

If the grid is:

Then some monochromatic squares include:

• All 1×1 cells (each single cell is a monochromatic square).
• The 2×2 square in the top-left corner formed by 'a' .

Your function should return the total count of such monochromatic squares for a given input grid.