73 lines
1.5 KiB
Rust
73 lines
1.5 KiB
Rust
use std::collections::HashMap;
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use color_eyre::Result;
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type FishMap = HashMap<isize, isize>;
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pub fn solve() -> Result<()> {
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let input_data = include_str!("../../data/day_06.txt").trim();
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println!("Day 06 Part 1: {}", part_1(input_data)?);
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println!("Day 06 Part 2: {}", part_2(input_data)?);
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Ok(())
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}
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fn part_1(input: &str) -> Result<isize> {
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let mut fishes = parse_fishes(input)?;
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for _ in 0..80 {
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fishes = simulate_fishes(fishes);
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}
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Ok(count_fishes(fishes))
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}
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fn part_2(input: &str) -> Result<isize> {
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let mut fishes = parse_fishes(input)?;
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for _ in 0..256 {
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fishes = simulate_fishes(fishes);
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}
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Ok(count_fishes(fishes))
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}
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fn parse_fishes(input: &str) -> Result<FishMap> {
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let mut fishes = FishMap::new();
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let individual_fishes = input
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.split(",")
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.map(str::parse)
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.collect::<Result<Vec<_>, _>>()?;
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for fish in individual_fishes {
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let amount = fishes.entry(fish).or_default();
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*amount += 1;
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}
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Ok(fishes)
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}
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fn count_fishes(fishes: FishMap) -> isize {
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fishes.into_iter().map(|(_, amount)| amount).sum()
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}
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fn simulate_fishes(fishes: FishMap) -> FishMap {
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let mut new_fishes = HashMap::new();
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for (mut timer, amount) in fishes {
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timer -= 1;
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if timer < 0 {
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let new_fish = new_fishes.entry(8).or_default();
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*new_fish += amount;
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let reset_fish = new_fishes.entry(6).or_default();
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*reset_fish += amount;
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} else {
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let current_fish = new_fishes.entry(timer).or_default();
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*current_fish += amount;
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}
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}
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new_fishes
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}
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