Much faster approach that deduplicates rows

Author: maneatingape

README.md

@@ -129,7 +129,7 @@ Performance is reasonable even on older hardware, for example a 2011 MacBook Pro
 | 20 | [Pulse Propagation](https://adventofcode.com/2023/day/20) | [Source](src/year2023/day20.rs) | 6 |
 | 21 | [Step Counter](https://adventofcode.com/2023/day/21) | [Source](src/year2023/day21.rs) | 182 |
 | 22 | [Sand Slabs](https://adventofcode.com/2023/day/22) | [Source](src/year2023/day22.rs) | 54 |
-| 23 | [A Long Walk](https://adventofcode.com/2023/day/23) | [Source](src/year2023/day23.rs) | 640 |
+| 23 | [A Long Walk](https://adventofcode.com/2023/day/23) | [Source](src/year2023/day23.rs) | 68 |
 | 24 | [Never Tell Me The Odds](https://adventofcode.com/2023/day/24) | [Source](src/year2023/day24.rs) | 95 |
 | 25 | [Snowverload](https://adventofcode.com/2023/day/25) | [Source](src/year2023/day25.rs) | 179 |