Fix the Spaces

Published Difficulty: Medium

Algorithm X Complexity: Straightforward

Overview

Two years passed between my original solution to this puzzle and my new approach using Algorithm X. My memory may not be as sharp as it once was, but I clearly remember enjoying the challenge. Looking back at that old code, it’s obvious I poured a lot of thought into logically narrowing down possibilities to reach a solution. With a little review, I’m confident I could still follow what it’s doing.

In contrast, it took me only a few minutes to construct an exact cover solution with Algorithm X. It looks like so many other solutions I’ve built since. The joy this time isn’t in the grind — it’s in the grace. There’s real satisfaction in watching a medium-difficulty puzzle fall quickly and elegantly. It feels like playing 2-on-2 basketball with a 7-foot-3 teammate who dunks every pass I toss.