janezicmatej
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aoc2023
generated from janezicmatej/aoc-template
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solution: day 20 clean

This commit is contained in:
Matej Janezic 2023-12-20 22:53:54 +01:00
parent 000003704a
commit 0000038000
Signed by: janezicmatej
GPG Key ID: 4298E230ED37B2C0
1 changed files with 29 additions and 18 deletions
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49
src/bin/20.rs
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@ -80,7 +80,7 @@ fn parse_input(input: &str) -> Vec<Node> {
nodes
}
pub fn cycle(input: &str, cycle_len: usize) -> (usize, usize) {
pub fn cycle(input: &str, button_presses: Option<usize>) -> usize {
let mut nodes = parse_input(input);
let mut graph = vec![vec![false; nodes.len()]; nodes.len()];
@ -95,8 +95,16 @@ pub fn cycle(input: &str, cycle_len: usize) -> (usize, usize) {
.index;
let mut hm = HashMap::new();
let critical_node = nodes[0].inputs.first().copied();
let critical_inputs = critical_node.map(|x| nodes[x].inputs.len());
for i in 1..=button_presses.unwrap_or(usize::MAX) {
if let Some(c) = critical_inputs {
if button_presses.is_none() && hm.values().len() == c {
return hm.values().copied().reduce(lcm).unwrap_or(0);
}
}
for i in 1..=cycle_len {
let mut stack = VecDeque::from([(broadcaster, false)]);
while let Some((index, signal)) = stack.pop_front() {
@ -112,17 +120,17 @@ pub fn cycle(input: &str, cycle_len: usize) -> (usize, usize) {
match node.module {
Module::Output => (),
Module::Broadcaster => {
for dest_index in node.outputs.iter() {
stack.push_back((*dest_index, false));
for dest_index in node.outputs.iter().copied() {
stack.push_back((dest_index, false));
}
}
Module::FlipFlop(high) => {
if !signal {
let signal = !high;
for dest_index in nodes[index].outputs.iter() {
graph[index][*dest_index] = signal;
stack.push_back((*dest_index, signal));
for dest_index in nodes[index].outputs.iter().copied() {
graph[index][dest_index] = signal;
stack.push_back((dest_index, signal));
}
new_module = Some(Module::FlipFlop(signal));
@ -131,21 +139,24 @@ pub fn cycle(input: &str, cycle_len: usize) -> (usize, usize) {
Module::Conjuction => {
let mut all = true;
for in_index in nodes[index].inputs.iter() {
all &= graph[*in_index][index];
for in_index in nodes[index].inputs.iter().copied() {
all &= graph[in_index][index];
}
for dest_index in nodes[index].outputs.iter().copied() {
if dest_index == 0 {
for in_index in nodes[index].inputs.iter() {
if graph[*in_index][index] {
hm.entry(*in_index).or_insert(i);
}
}
}
graph[index][dest_index] = !all;
stack.push_back((dest_index, !all));
}
if let Some(c) = critical_node {
if index == c {
for in_index in nodes[index].inputs.iter().copied() {
if graph[in_index][index] {
hm.entry(in_index).or_insert(i);
}
}
}
}
}
}
@ -156,14 +167,14 @@ pub fn cycle(input: &str, cycle_len: usize) -> (usize, usize) {
}
}
(highs * lows, hm.values().copied().reduce(lcm).unwrap_or(0))
highs * lows
}
pub fn part_one(input: &str) -> Option<usize> {
Some(cycle(input, 1000).0)
Some(cycle(input, Some(1000)))
}
pub fn part_two(input: &str) -> Option<usize> {
Some(cycle(input, 10_000).1)
Some(cycle(input, None))
}
aoc::solution!(20);