Count Same-Color Squares in a Grid

Problem: Count Same-Color Squares in a Grid You are given a 2D grid grid of characters. Each cell contains an uppercase letter (e.g., A/B/C/D) representing a color. The grid size is arbitrary (no fixed limit on rows/columns). Count how many same-color square regions exist in the grid. A square region is a contiguous k x k (k >= 1) submatrix such that all cells inside it have the exact same character. Input (stdin) The first line contains two integers m n, the number of rows and columns. The next m lines each contain a string of length n with uppercase letters. Output (stdout) Output a single integer: the total number of same-color square regions. Constraints 1 <= m, n <= 2000 (can be discussed for larger sizes in interview) Example Input: 3 4 AABB AABB AAAA Output: 13 Explanation (informal): All 1x1 cells are squares: 12 There is one 2x2 same-color square at the top-left No larger same-color squares Total: 12 + 1 = 13 Example Input 1 1 A Output 1