2019: day07: part 2

This commit is contained in:
Antoine Martin 2019-12-07 23:04:50 +01:00
parent 27f6a072da
commit 83e99215fb
2 changed files with 110 additions and 5 deletions

View file

@ -12,6 +12,7 @@ pub fn run() -> Result<String> {
let mut res = String::with_capacity(128);
writeln!(res, "part 1: {}", part1(INPUT)?)?;
writeln!(res, "part 2: {}", part2(INPUT)?)?;
Ok(res)
}
@ -67,6 +68,79 @@ fn part1(input: &str) -> Result<i64> {
Ok(res)
}
fn part2(input: &str) -> Result<i64> {
let memory = parse_memory(input)?;
let combinations = permutations(&[5, 6, 7, 8, 9]);
let mut res = 0;
for combination in combinations {
let intcodes = &mut [
Intcode::with_memory(memory.clone()),
Intcode::with_memory(memory.clone()),
Intcode::with_memory(memory.clone()),
Intcode::with_memory(memory.clone()),
Intcode::with_memory(memory.clone()),
];
for (phase, intcode) in combination.iter().zip(intcodes.iter_mut()) {
intcode.add_input(*phase);
}
intcodes[0].add_input(0);
let mut signal = None;
let mut num_halted = 0;
loop {
for i in 0..(intcodes.len() - 1) {
let (first, second) = intcodes.split_at_mut(i + 1);
let intcode = &mut first[i];
let next = &mut second[0];
let halted = intcode.run_and_wait()?;
if halted {
num_halted += 1;
}
for out in intcode.output.iter() {
next.add_input(*out);
}
intcode.output.clear();
}
let last_index = intcodes.len() - 1;
let (first, second) = intcodes.split_at_mut(last_index);
let first = &mut first[0];
let last = &mut second[0];
let halted = last.run_and_wait()?;
if halted {
let out = last
.output
.last()
.copied()
.ok_or_else(|| err!("last amplifier halted without output"))?;
signal = Some(out);
} else {
for out in last.output.iter() {
first.add_input(*out);
}
last.output.clear();
}
if let Some(signal) = signal {
res = std::cmp::max(res, signal);
break;
}
if num_halted >= 4 {
return Err(err!("all non final amplifiers halted, feedback loop stuck"));
}
}
}
Ok(res)
}
#[cfg(test)]
mod tests {
use super::*;
@ -87,4 +161,19 @@ mod tests {
fn part1_real() {
assert_eq!(part1(INPUT).unwrap(), 844468);
}
const PROVIDED4: &str =
"3,26,1001,26,-4,26,3,27,1002,27,2,27,1,27,26,27,4,27,1001,28,-1,28,1005,28,6,99,0,0,5";
const PROVIDED5: &str = "3,52,1001,52,-5,52,3,53,1,52,56,54,1007,54,5,55,1005,55,26,1001,54,-5,54,1105,1,12,1,53,54,53,1008,54,0,55,1001,55,1,55,2,53,55,53,4,53,1001,56,-1,56,1005,56,6,99,0,0,0,0,10";
#[test]
fn part2_provided() {
assert_eq!(part2(PROVIDED4).unwrap(), 139629729);
assert_eq!(part2(PROVIDED5).unwrap(), 18216);
}
#[test]
fn part2_real() {
assert_eq!(part2(INPUT).unwrap(), 4215746);
}
}

View file

@ -24,12 +24,14 @@ enum Opcode {
Halt,
}
#[derive(Debug)]
pub struct Intcode {
pub memory: Vec<i64>,
input: Vec<i64>,
pub output: Vec<i64>,
ip: usize,
next_input: usize,
wait_input: bool,
}
impl Intcode {
@ -46,6 +48,7 @@ impl Intcode {
output: Vec::new(),
ip: 0,
next_input: 0,
wait_input: false,
}
}
@ -136,7 +139,7 @@ impl Intcode {
}
}
pub fn run(&mut self) -> Result<()> {
fn exec(&mut self) -> Result<bool> {
loop {
if self.ip >= self.memory.len() {
return Err(err!("reached end of program without halting"));
@ -165,10 +168,12 @@ impl Intcode {
let input = if self.next_input < self.input.len() {
let res = self.input[self.next_input];
self.next_input += 1;
Ok(res)
res
} else if self.wait_input {
break Ok(false);
} else {
Err(err!("tried to read input but it was empty"))
}?;
break Err(err!("tried to read input but it was empty"));
};
dst.set(&mut self.memory, input)?;
self.ip += 2;
@ -223,11 +228,22 @@ impl Intcode {
self.ip += 4;
}
Opcode::Halt => break Ok(()),
Opcode::Halt => break Ok(true),
}
}
}
pub fn run_and_wait(&mut self) -> Result<bool> {
self.wait_input = true;
self.exec()
}
pub fn run(&mut self) -> Result<()> {
self.wait_input = false;
self.exec()?;
Ok(())
}
pub fn get_day02_output(&self) -> Option<i64> {
self.memory.get(0).copied()
}