Year 2019 Day 7

README.md

@@ -199,6 +199,7 @@ pie
 | 4 | [Secure Container](https://adventofcode.com/2019/day/4) | [Source](src/year2019/day04.rs) | 7 |
 | 5 | [Sunny with a Chance of Asteroids](https://adventofcode.com/2019/day/5) | [Source](src/year2019/day05.rs) | 34 |
 | 6 | [Universal Orbit Map](https://adventofcode.com/2019/day/6) | [Source](src/year2019/day06.rs) | 28 |
+| 7 | [Amplification Circuit](https://adventofcode.com/2019/day/7) | [Source](src/year2019/day07.rs) | 30000 |
 
 ## 2015
 

benches/benchmark.rs

@@ -126,6 +126,7 @@ mod year2019 {
     benchmark!(year2019, day04);
     benchmark!(year2019, day05);
     benchmark!(year2019, day06);
+    benchmark!(year2019, day07);
 }
 
 mod year2015 {

input/year2019/day07.txt

@@ -0,0 +1 @@
+3,8,1001,8,10,8,105,1,0,0,21,46,59,84,93,102,183,264,345,426,99999,3,9,1002,9,4,9,1001,9,3,9,102,2,9,9,1001,9,5,9,102,3,9,9,4,9,99,3,9,1002,9,3,9,101,4,9,9,4,9,99,3,9,1002,9,4,9,1001,9,4,9,102,2,9,9,1001,9,2,9,1002,9,3,9,4,9,99,3,9,1001,9,5,9,4,9,99,3,9,1002,9,4,9,4,9,99,3,9,101,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,99,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,99,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,99

src/lib.rs

@@ -179,6 +179,7 @@ pub mod year2019 {
     pub mod day04;
     pub mod day05;
     pub mod day06;
+    pub mod day07;
 }
 
 /// # Help Santa by solving puzzles to fix the weather machine's snow function.

src/main.rs

@@ -166,6 +166,7 @@ fn all_solutions() -> Vec<Solution> {
         solution!(year2019, day04),
         solution!(year2019, day05),
         solution!(year2019, day06),
+        solution!(year2019, day07),
         // 2015
         solution!(year2015, day01),
         solution!(year2015, day02),

src/year2019/day05.rs

@@ -3,7 +3,7 @@ use crate::util::parse::*;
 use std::sync::mpsc::*;
 use std::thread;
 
-struct IntCode {
+pub struct IntCode {
     pc: usize,
     code: Vec<i64>,
     input_rx: Receiver<i64>,
@@ -13,7 +13,7 @@ struct IntCode {
 impl IntCode {
     const FACTOR: [i64; 4] = [0, 100, 1000, 10000];
 
-    fn spawn(code: &[i64]) -> (Sender<i64>, Receiver<i64>) {
+    pub fn spawn(code: &[i64]) -> (Sender<i64>, Receiver<i64>) {
         let pc = 0;
         let code = code.to_vec();
         let (input_tx, input_rx) = channel();

src/year2019/day07.rs

@@ -0,0 +1,71 @@
+//! # Amplification Circuit
+//!
+//! Brute force solution for both parts using the utility [`permutations`] method to test each of
+//! the possible 5! or 120 permutations of the phase settings.
+//!
+//! Even though each `IntCode` computer runs in parallel in a separate thread the [`Sender`] and
+//! [`Receiver`] objects synchronize messages between threads, blocking each thread when
+//! input is needed.
+//!
+//! [`permutations`]: crate::util::slice
+//! [`Sender`]: std::sync::mpsc::Sender
+//! [`Receiver`]: std::sync::mpsc::Receiver
+use super::day05::IntCode;
+use crate::util::parse::*;
+use crate::util::slice::*;
+
+pub fn parse(input: &str) -> Vec<i64> {
+    input.iter_signed::<i64>().collect()
+}
+
+pub fn part1(input: &[i64]) -> i64 {
+    let mut result = 0;
+
+    let sequence = |slice: &[i64]| {
+        let mut signal = 0;
+
+        // Send exactly 2 inputs and receive exactly 1 output per amplifier.
+        for &phase in slice {
+            let (tx, rx) = IntCode::spawn(input);
+            let _ = tx.send(phase);
+            let _ = tx.send(signal);
+            signal = rx.recv().unwrap();
+        }
+
+        result = result.max(signal);
+    };
+
+    [0, 1, 2, 3, 4].permutations(sequence);
+    result
+}
+
+pub fn part2(input: &[i64]) -> i64 {
+    let mut result = 0;
+
+    let feedback = |slice: &[i64]| {
+        let (senders, receivers): (Vec<_>, Vec<_>) = (0..5).map(|_| IntCode::spawn(input)).unzip();
+
+        // Send each initial phase setting exactly once.
+        for (tx, &phase) in senders.iter().zip(slice.iter()) {
+            let _ = tx.send(phase);
+        }
+
+        // Chain amplifier inputs and ouputs in a loop until all threads finish.
+        let mut signal = 0;
+
+        'outer: loop {
+            for (tx, rx) in senders.iter().zip(receivers.iter()) {
+                let _ = tx.send(signal);
+                let Ok(next) = rx.recv() else {
+                    break 'outer;
+                };
+                signal = next;
+            }
+        }
+
+        result = result.max(signal);
+    };
+
+    [5, 6, 7, 8, 9].permutations(feedback);
+    result
+}

tests/test.rs

@@ -89,6 +89,7 @@ mod year2019 {
     mod day04_test;
     mod day05_test;
     mod day06_test;
+    mod day07_test;
 }
 
 mod year2015 {

tests/year2019/day07_test.rs

@@ -0,0 +1,20 @@
+use aoc::year2019::day07::*;
+
+const FIRST_EXAMPLE: &str = "\
+3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0";
+
+const SECOND_EXAMPLE: &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";
+
+#[test]
+fn part1_test() {
+    let input = parse(FIRST_EXAMPLE);
+    assert_eq!(part1(&input), 43210);
+}
+
+#[test]
+fn part2_test() {
+    let input = parse(SECOND_EXAMPLE);
+    assert_eq!(part2(&input), 139629729);
+}