2019: day07: part 1

aoc2019/src/day07.rs

@@ -0,0 +1,90 @@
+use std::collections::VecDeque;
+use std::fmt::Write;
+
+use aoc::err;
+use aoc::Result;
+
+use crate::intcode::{parse_memory, Intcode};
+
+const INPUT: &str = include_str!("../input/day07.txt");
+
+pub fn run() -> Result<String> {
+    let mut res = String::with_capacity(128);
+
+    writeln!(res, "part 1: {}", part1(INPUT)?)?;
+
+    Ok(res)
+}
+
+fn permutations_rec(used: &mut Vec<i64>, available: &mut VecDeque<i64>, res: &mut Vec<Vec<i64>>) {
+    if available.is_empty() {
+        res.push(used.clone());
+    } else {
+        for _ in 0..available.len() {
+            used.push(available.pop_front().unwrap());
+            permutations_rec(used, available, res);
+            available.push_back(used.pop().unwrap());
+        }
+    }
+}
+
+fn permutations(array: &[i64]) -> Vec<Vec<i64>> {
+    let mut res = Vec::new();
+
+    permutations_rec(
+        &mut Vec::new(),
+        &mut VecDeque::from(array.to_vec()),
+        &mut res,
+    );
+
+    res
+}
+
+fn part1(input: &str) -> Result<i64> {
+    let memory = parse_memory(input)?;
+
+    let combinations = permutations(&[0, 1, 2, 3, 4]);
+
+    let mut res = 0;
+    for combination in combinations {
+        let mut output = 0;
+        for phase in combination.iter() {
+            let mut intcode = Intcode::with_memory(memory.clone());
+
+            intcode.add_input(*phase);
+            intcode.add_input(output);
+
+            intcode.run()?;
+
+            output = intcode
+                .get_day05_output()
+                .ok_or_else(|| err!("no output at end of pipeline!"))?;
+        }
+
+        res = std::cmp::max(res, output);
+    }
+
+    Ok(res)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const PROVIDED1: &str = "3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0";
+    const PROVIDED2: &str =
+        "3,23,3,24,1002,24,10,24,1002,23,-1,23,101,5,23,23,1,24,23,23,4,23,99,0,0";
+    const PROVIDED3: &str = "3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0";
+
+    #[test]
+    fn part1_provided() {
+        assert_eq!(part1(PROVIDED1).unwrap(), 43210);
+        assert_eq!(part1(PROVIDED2).unwrap(), 54321);
+        assert_eq!(part1(PROVIDED3).unwrap(), 65210);
+    }
+
+    #[test]
+    fn part1_real() {
+        assert_eq!(part1(INPUT).unwrap(), 844468);
+    }
+}

aoc2019/src/lib.rs

@@ -6,3 +6,4 @@ pub mod day03;
 pub mod day04;
 pub mod day05;
 pub mod day06;
+pub mod day07;

aoc2019/src/main.rs

@@ -7,6 +7,7 @@ use aoc2019::day03;
 use aoc2019::day04;
 use aoc2019::day05;
 use aoc2019::day06;
+use aoc2019::day07;
 
 fn main() -> Result<()> {
     let days: &[DayFunc] = &[
@@ -16,6 +17,7 @@ fn main() -> Result<()> {
         day04::run,
         day05::run,
         day06::run,
+        day07::run,
     ];
 
     aoc::run(days)