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#![allow(dead_code)]
#![allow(unused_variables)]
use advent_of_code::prelude::*;
#[derive(Clone)]
pub enum Monkey {
Num(i64),
Add(String, String),
Sub(String, String),
Mul(String, String),
Div(String, String),
Human,
}
pub struct NamedMonkey(String, Monkey);
impl std::str::FromStr for NamedMonkey {
type Err = Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let cap = regex_captures!(r"^(\w+): (\d+|\w+ [+*/-] \w+)$", s)
.ok_or_else(|| anyhow!("failed to parse"))?;
let name = cap[1].to_string();
if let Ok(n) = cap[2].parse::<i64>() {
Ok(NamedMonkey(name, Monkey::Num(n)))
} else {
let mut parts = cap[2].split_whitespace();
let monkey1 = parts.next().unwrap();
let op = parts.next().unwrap();
let monkey2 = parts.next().unwrap();
match op {
"+" => Ok(NamedMonkey(
name,
Monkey::Add(monkey1.to_string(), monkey2.to_string()),
)),
"-" => Ok(NamedMonkey(
name,
Monkey::Sub(monkey1.to_string(), monkey2.to_string()),
)),
"*" => Ok(NamedMonkey(
name,
Monkey::Mul(monkey1.to_string(), monkey2.to_string()),
)),
"/" => Ok(NamedMonkey(
name,
Monkey::Div(monkey1.to_string(), monkey2.to_string()),
)),
_ => unreachable!(),
}
}
}
}
impl Monkey {
fn eval(&self, monkeys: &HashMap<String, Monkey>) -> Option<i64> {
match self {
Self::Num(n) => Some(*n),
Self::Add(n, m) => {
monkeys.get(n).unwrap().eval(monkeys).and_then(|n| {
monkeys.get(m).unwrap().eval(monkeys).map(|m| n + m)
})
}
Self::Sub(n, m) => {
monkeys.get(n).unwrap().eval(monkeys).and_then(|n| {
monkeys.get(m).unwrap().eval(monkeys).map(|m| n - m)
})
}
Self::Mul(n, m) => {
monkeys.get(n).unwrap().eval(monkeys).and_then(|n| {
monkeys.get(m).unwrap().eval(monkeys).map(|m| n * m)
})
}
Self::Div(n, m) => {
monkeys.get(n).unwrap().eval(monkeys).and_then(|n| {
monkeys.get(m).unwrap().eval(monkeys).map(|m| n / m)
})
}
Self::Human => None,
}
}
fn is_num(&self) -> bool {
matches!(self, Monkey::Num(_))
}
fn invert(&self, monkeys: &HashMap<String, Monkey>, mut val: i64) -> i64 {
let mut monkey = self;
loop {
match monkey {
Monkey::Num(n) => panic!("found num?"),
Monkey::Add(n, m) => {
let monkey1 = monkeys.get(n).unwrap();
let monkey2 = monkeys.get(m).unwrap();
if let Monkey::Num(n) = monkey1 {
monkey = monkey2;
val -= n;
} else if let Monkey::Num(n) = monkey2 {
monkey = monkey1;
val -= n;
} else {
panic!("not simplified?");
}
}
Monkey::Sub(n, m) => {
let monkey1 = monkeys.get(n).unwrap();
let monkey2 = monkeys.get(m).unwrap();
if let Monkey::Num(n) = monkey1 {
monkey = monkey2;
val = n - val;
} else if let Monkey::Num(n) = monkey2 {
monkey = monkey1;
val += n;
} else {
panic!("not simplified?");
}
}
Monkey::Mul(n, m) => {
let monkey1 = monkeys.get(n).unwrap();
let monkey2 = monkeys.get(m).unwrap();
if let Monkey::Num(n) = monkey1 {
monkey = monkey2;
val /= n;
} else if let Monkey::Num(n) = monkey2 {
monkey = monkey1;
val /= n;
} else {
panic!("not simplified?");
}
}
Monkey::Div(n, m) => {
let monkey1 = monkeys.get(n).unwrap();
let monkey2 = monkeys.get(m).unwrap();
if let Monkey::Num(n) = monkey1 {
monkey = monkey2;
val = n / val;
} else if let Monkey::Num(n) = monkey2 {
monkey = monkey1;
val *= n;
} else {
panic!("not simplified?");
}
}
Monkey::Human => return val,
}
}
}
}
pub fn parse(fh: File) -> Result<HashMap<String, Monkey>> {
Ok(parse::lines(fh)
.map(|NamedMonkey(name, monkey)| (name, monkey))
.collect())
}
pub fn part1(monkeys: HashMap<String, Monkey>) -> Result<i64> {
Ok(monkeys
.get("root")
.ok_or_else(|| anyhow!("couldn't find root"))?
.eval(&monkeys)
.unwrap())
}
pub fn part2(mut monkeys: HashMap<String, Monkey>) -> Result<i64> {
monkeys.insert("humn".to_string(), Monkey::Human);
simplify(&mut monkeys);
let root = monkeys
.get("root")
.ok_or_else(|| anyhow!("couldn't find root"))?;
let (monkey1, monkey2) = match root {
Monkey::Add(n, m) => {
(monkeys.get(n).unwrap(), monkeys.get(m).unwrap())
}
Monkey::Sub(n, m) => {
(monkeys.get(n).unwrap(), monkeys.get(m).unwrap())
}
Monkey::Mul(n, m) => {
(monkeys.get(n).unwrap(), monkeys.get(m).unwrap())
}
Monkey::Div(n, m) => {
(monkeys.get(n).unwrap(), monkeys.get(m).unwrap())
}
_ => panic!("wrong root"),
};
let (val, monkey_human) = if let Monkey::Num(n) = monkey1 {
assert!(!matches!(monkey2, Monkey::Num(_)));
(n, monkey2)
} else if let Monkey::Num(n) = monkey2 {
assert!(!matches!(monkey1, Monkey::Num(_)));
(n, monkey1)
} else {
panic!("wrong monkeys")
};
Ok(monkey_human.invert(&monkeys, *val))
}
fn simplify(monkeys: &mut HashMap<String, Monkey>) {
loop {
let mut found = None;
for (name, monkey) in monkeys.iter() {
if matches!(monkey, Monkey::Num(_) | Monkey::Human) {
continue;
}
if let Some(n) = monkey.eval(monkeys) {
found = Some((name.to_string(), n));
break;
}
}
if let Some((name, n)) = found {
*monkeys.get_mut(&name).unwrap() = Monkey::Num(n);
} else {
break;
}
}
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2022, 21).unwrap()).unwrap()).unwrap(),
10037517593724
);
assert_eq!(
part2(parse(parse::data(2022, 21).unwrap()).unwrap()).unwrap(),
3272260914328
);
}
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