Module aoc::year2021::day14

Extended Polymerization

The key insight to this problem is the same as Day 6. We track the total number of each pair as the positions don’t affect the final result.

Fixed sized arrays are used for speed as we know that the elements are limited to 26 values and the possible pairs to 26 * 26 values.

Structs

• Input
• Rule

Functions

• element 🔒
  Convert a single uppercase ASCII character to an index between 0 and 25
• pair 🔒
  Convert two uppercase ASCII characters to an index between 0 and 675.
• parse
  Count the initial pairs and elements and parse each instruction into a Rule struct.
• part1
  Apply 10 steps.
• part2
  Apply 40 steps.
• steps 🔒
  Simulate an arbitrary number of steps.

Type Aliases

• Elements 🔒
• Pairs 🔒
• Rules 🔒