Day 11, puzzle 2

Cargo.lock

@@ -18,9 +18,16 @@ dependencies = [
  "env_logger",
  "itertools",
  "log",
+ "num",
  "regex",
 ]
 
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -79,6 +86,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "fuchsia-cprng"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
+
 [[package]]
 name = "hermit-abi"
 version = "0.2.6"
@@ -152,6 +165,121 @@ version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
+[[package]]
+name = "num"
+version = "0.1.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4703ad64153382334aa8db57c637364c322d3372e097840c72000dabdcf6156e"
+dependencies = [
+ "num-bigint",
+ "num-complex",
+ "num-integer",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+]
+
+[[package]]
+name = "num-bigint"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e63899ad0da84ce718c14936262a41cee2c79c981fc0a0e7c7beb47d5a07e8c1"
+dependencies = [
+ "num-integer",
+ "num-traits",
+ "rand",
+ "rustc-serialize",
+]
+
+[[package]]
+name = "num-complex"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b288631d7878aaf59442cffd36910ea604ecd7745c36054328595114001c9656"
+dependencies = [
+ "num-traits",
+ "rustc-serialize",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "225d3389fb3509a24c93f5c29eb6bde2586b98d9f016636dff58d7c6f7569cd9"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-iter"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d03e6c028c5dc5cac6e2dec0efda81fc887605bb3d884578bb6d6bf7514e252"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.1.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee314c74bd753fc86b4780aa9475da469155f3848473a261d2d18e35245a784e"
+dependencies = [
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+ "rustc-serialize",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "578ede34cf02f8924ab9447f50c28075b4d3e5b269972345e7e0372b38c6cdcd"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "rand"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "552840b97013b1a26992c11eac34bdd778e464601a4c2054b5f0bff7c6761293"
+dependencies = [
+ "fuchsia-cprng",
+ "libc",
+ "rand_core 0.3.1",
+ "rdrand",
+ "winapi",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a6fdeb83b075e8266dcc8762c22776f6877a63111121f5f8c7411e5be7eed4b"
+dependencies = [
+ "rand_core 0.4.2",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c33a3c44ca05fa6f1807d8e6743f3824e8509beca625669633be0acbdf509dc"
+
+[[package]]
+name = "rdrand"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "678054eb77286b51581ba43620cc911abf02758c91f93f479767aed0f90458b2"
+dependencies = [
+ "rand_core 0.3.1",
+]
+
 [[package]]
 name = "regex"
 version = "1.7.0"
@@ -169,6 +297,12 @@ version = "0.6.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "456c603be3e8d448b072f410900c09faf164fbce2d480456f50eea6e25f9c848"
 
+[[package]]
+name = "rustc-serialize"
+version = "0.3.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dcf128d1287d2ea9d80910b5f1120d0b8eede3fbf1abe91c40d39ea7d51e6fda"
+
 [[package]]
 name = "rustix"
 version = "0.36.5"

Cargo.toml

@@ -10,6 +10,7 @@ regex = "1"
 itertools = "^0.10"
 log = "^0.4"
 env_logger = "^0.10"
+num = "^0.1"
 
 [[bin]]
 name = "d1p1"

src/bin/d11p1.rs

@@ -10,8 +10,8 @@ pub fn main() {
 
     let monkeys = day11::parse_monkeys(&util::parse_input());
 
-    for _ in 0..20 {
+    for _ in 0..N_ROUNDS {
-        day11::do_round(&monkeys);
+        day11::do_round(&monkeys, true);
     }
 
     println!(

src/bin/d11p2.rs

@@ -0,0 +1,22 @@
+use aoc22::{
+    day11::{self, monkey_business},
+    util,
+};
+
+const N_ROUNDS: usize = 10000;
+
+pub fn main() {
+    env_logger::init();
+
+    let monkeys = day11::parse_monkeys(&util::parse_input());
+
+    for _ in 0..N_ROUNDS {
+        day11::do_round(&monkeys, false);
+    }
+
+    println!(
+        "Monkey business after {} rounds is {}",
+        N_ROUNDS,
+        monkey_business(&monkeys)
+    );
+}

src/day11.rs

@@ -1,6 +1,7 @@
-use std::{borrow::BorrowMut, cell::RefCell, collections::VecDeque};
+use std::{cell::RefCell, collections::VecDeque};
 
 use itertools::Itertools;
+use num::Integer;
 use regex::Regex;
 
 #[derive(Debug)]
@@ -137,7 +138,12 @@ fn parse_op_kind(s: &str) -> OpKind {
     }
 }
 
-pub fn do_round(monkeys: &Vec<RefCell<Monkey>>) {
+pub fn do_round(monkeys: &Vec<RefCell<Monkey>>, do_worry: bool) {
+    let overall_mod = monkeys
+        .iter()
+        .map(|m| m.borrow().test.div)
+        .reduce(|acc, div| acc.lcm(&div))
+        .unwrap();
     for n in 0..monkeys.len() {
         let mut monkey = monkeys.get(n).unwrap().borrow_mut();
         log::debug!("Monkey {}", n);
@@ -145,21 +151,23 @@ pub fn do_round(monkeys: &Vec<RefCell<Monkey>>) {
             monkey.activity += 1;
             let mut item = monkey.items.pop_front().unwrap();
             log::debug!("  Monkey inspects an item with a worry level of {}.", item);
-            item = run_op(&monkey.op, item);
+            item = run_op(&monkey.op, item) % overall_mod;
             log::debug!("    Worry level increases to {}.", item);
+            if do_worry {
                 item /= 3;
                 log::debug!(
                     "    Monkey gets bored with item. Worry level is divided by 3 to {}.",
                     item
                 );
+            }
             let target = if item % monkey.test.div == 0 {
+                log::debug!("Current worry level is divisible by {}", monkey.test.div);
+                monkey.test.target_true
+            } else {
                 log::debug!(
                     "Current worry level is not divisible by {}",
                     monkey.test.div
                 );
-                monkey.test.target_true
-            } else {
-                log::debug!("Current worry level is divisible by {}", monkey.test.div);
                 monkey.test.target_false
             };
             log::debug!(