Coding

Hollow Square Pattern

Asked atRRateGain

1Give yourself 5 minutes

2Answer out loud, not in your head

3Then compare with the answer below

Stuck? Show a way to structure it+

01Write the output geometry before coding
02Identify boundary cells from row and column indices
03Use one loop per row and one per column
04Keep spacing and newline behavior explicit
05Check the smallest valid size and even or odd dimensions when relevant

Reference answer

Treat “Hollow Square 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.

Then expect these follow-ups

What constraint would change your chosen approach?
Tests: constraint adaptation
How would you test the edge cases before implementation?
Tests: implementation extension

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