Hourglass Pattern

Treat “Hourglass Pattern” as an output-geometry exercise, not an opportunity to memorize a string. First confirm the requested dimensions and characters, since pattern prompts often differ on spacing. For a hollow square of size n, print the border when row or column is 0 or n - 1 and spaces elsewhere. For an hourglass, derive each row’s leading indentation and printed width from its distance to the middle, then mirror the rule. Describe the row/column condition before writing loops so off-by-one errors are visible. Keep output construction separate from display if the environment tests returned strings. Test the smallest legal n, n = 2, odd and even sizes if allowed, and exact trailing-space requirements. These patterns take O(n²) output work because that many character positions may be emitted.