day(11): refactor simulation

Signed-off-by: Matej Focko <mfocko@redhat.com>

src/bin/day11.rs

@@ -119,7 +119,7 @@ impl FromStr for Monkey {
     }
 }
 
-fn round(monkeys: &mut Input, lcm: usize, div: bool) {
+fn round(monkeys: &mut Input, lcm: usize, modular: bool) {
     let mut q: VecDeque<(usize, usize)> = VecDeque::new();
 
     for i in 0..monkeys.len() {
@@ -127,10 +127,11 @@ fn round(monkeys: &mut Input, lcm: usize, div: bool) {
 
         for j in 0..m.items.len() {
             let mut worry = m.operation.apply(m.items[j]);
-            if div {
+            if modular {
+                worry %= lcm;
+            } else {
                 worry /= 3;
             }
-            worry %= lcm;
 
             q.push_back((m.test.get(worry), worry));
             m.inspections += 1;
@@ -156,36 +157,7 @@ fn euclid(a: usize, b: usize) -> usize {
     a
 }
 
-struct Day11;
+fn simulate_rounds(input: &Input, rounds: usize, modular: bool) -> Output {
-impl Solution<Input, Output> for Day11 {
-    fn parse_input<P: AsRef<Path>>(pathname: P) -> Input {
-        file_to_string(pathname)
-            .split("\n\n")
-            .map(|m| m.parse().unwrap())
-            .collect_vec()
-    }
-
-    fn part_1(input: &Input) -> Output {
-        let mut monkeys = input.clone();
-
-        let lcm = monkeys
-            .iter()
-            .map(|m| m.test.0)
-            .fold(1, |x, y| x * y / euclid(x, y));
-
-        for _ in 0..20 {
-            round(&mut monkeys, lcm, true);
-        }
-
-        monkeys
-            .iter()
-            .map(|m| m.inspections)
-            .sorted_by_key(|&i| Reverse(i))
-            .take(2)
-            .product()
-    }
-
-    fn part_2(input: &Input) -> Output {
     let mut monkeys = input.clone();
 
     let lcm = monkeys
@@ -197,8 +169,8 @@ impl Solution<Input, Output> for Day11 {
         1, 20, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 1000,
     ];
 
-        for r in 0..10000 {
+    for r in 0..rounds {
-            round(&mut monkeys, lcm, false);
+        round(&mut monkeys, lcm, modular);
 
         if inspect.contains(&(r + 1)) {
             debug!(
@@ -216,6 +188,23 @@ impl Solution<Input, Output> for Day11 {
         .take(2)
         .product()
 }
+
+struct Day11;
+impl Solution<Input, Output> for Day11 {
+    fn parse_input<P: AsRef<Path>>(pathname: P) -> Input {
+        file_to_string(pathname)
+            .split("\n\n")
+            .map(|m| m.parse().unwrap())
+            .collect_vec()
+    }
+
+    fn part_1(input: &Input) -> Output {
+        simulate_rounds(input, 20, false)
+    }
+
+    fn part_2(input: &Input) -> Output {
+        simulate_rounds(input, 10000, true)
+    }
 }
 
 fn main() -> Result<()> {