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|
use nom::{
branch::alt,
bytes::complete::tag,
character::complete::{line_ending, u64},
combinator::{map, value},
multi::separated_list1,
sequence::{pair, preceded, tuple},
IResult,
};
use std::fs;
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("inputs/day_11.txt")?;
let troop = MonkeyTroop::parser(&input).unwrap().1;
{
let mut troop_1 = troop.clone();
for _ in 0..20 {
troop_1.monkey_game_round(true);
}
dbg!(&troop_1.monkey_business_score());
}
{
let mut troop_2 = troop.clone();
for _ in 0..10000 {
troop_2.monkey_game_round(false);
}
dbg!(&troop_2.monkey_business_score());
}
Ok(())
}
#[derive(Debug, Clone)]
struct MonkeyTroop {
monkeys: Vec<Monkey>,
gcd: u64,
}
#[derive(Debug, Clone)]
struct Monkey {
items: Vec<u64>,
operation: Operation,
test_denominator: u64,
true_target: usize,
false_target: usize,
inspection_count: usize,
}
#[derive(Debug, Clone)]
enum Operation {
Add(u64),
Multiply(u64),
Square,
}
impl MonkeyTroop {
fn parser(input: &str) -> IResult<&str, Self> {
map(
separated_list1(pair(line_ending, line_ending), Monkey::parser),
|monkeys| MonkeyTroop {
gcd: monkeys.iter().map(|m| m.test_denominator).product(),
monkeys,
},
)(input)
}
fn monkey_game_round(&mut self, worry_reduction: bool) {
for monkey_i in 0..self.monkeys.len() {
self.monkeys[monkey_i].inspect_items(worry_reduction, self.gcd);
let items = std::mem::take(&mut self.monkeys[monkey_i].items);
let test_denominator = self.monkeys[monkey_i].test_denominator.clone();
let true_target = self.monkeys[monkey_i].true_target.clone();
let false_target = self.monkeys[monkey_i].false_target.clone();
for item in items {
let target_monkey = if item % test_denominator == 0 {
true_target
} else {
false_target
};
self.monkeys[target_monkey].items.push(item);
}
}
}
fn monkey_business_score(&self) -> usize {
let mut counts: Vec<usize> = self
.monkeys
.iter()
.map(|m| m.inspection_count.clone())
.collect();
counts.sort();
counts.reverse();
counts[0] * counts[1]
}
}
impl Monkey {
fn parser(input: &str) -> IResult<&str, Self> {
map(
tuple((
preceded(
tuple((
tag("Monkey "),
u64,
tag(":"),
line_ending,
tag(" Starting items: "),
)),
separated_list1(tag(", "), u64),
),
preceded(
pair(line_ending, tag(" Operation: new = old ")),
alt((
map(preceded(tag("+ "), u64), Operation::Add),
map(preceded(tag("* "), u64), Operation::Multiply),
value(Operation::Square, tag("* old")),
)),
),
preceded(pair(line_ending, tag(" Test: divisible by ")), u64),
preceded(pair(line_ending, tag(" If true: throw to monkey ")), u64),
preceded(
pair(line_ending, tag(" If false: throw to monkey ")),
u64,
),
)),
|(items, operation, test_denominator, true_target, false_target)| Monkey {
items,
operation,
test_denominator,
true_target: true_target as usize,
false_target: false_target as usize,
inspection_count: 0,
},
)(input)
}
fn inspect_items(&mut self, worry_reduction: bool, gcd: u64) {
for item in &mut self.items {
match self.operation {
Operation::Add(i) => *item += i,
Operation::Multiply(i) => *item *= i,
Operation::Square => *item = *item * *item,
};
if worry_reduction {
*item /= 3;
}
*item = *item % gcd;
}
self.inspection_count += self.items.len()
}
}
|
