day 11

Cool puzzle requiring a bit of thinking for the second part. Had a lot
of issues with rust's moving system in this one, had to read some docs
again. I think I understand it better after this one.

day_11/src/main.rs

@@ -1,3 +1,204 @@
-fn main() {
-    println!("Hello, world!");
+use std::ops::RangeInclusive;
+
+struct Monkey {
+    items: Vec<u64>,
+    operation: fn(u64) -> u64,
+    test_divisor: u64,
+    throw_true: usize,
+    throw_false: usize,
+    inspections: usize,
+}
+
+enum ManagementStrategy {
+    Div3,
+    Span,
+}
+
+// COULDN'T BE BOTHERED TO WRITE A PARSER FOR THIS DATA
+// FORMATTED IT USING VSCODE MULTICURSORS
+
+fn main() {
+    // CHANGE TO input_monkeys() TO USE PUZZLE INPUT
+    let monkeys = demo_monkeys();
+    println!(
+        "PART 1 {}",
+        parts(monkeys, 1..=20, ManagementStrategy::Div3)
+    );
+    // CHANGE TO input_monkeys() TO USE PUZZLE INPUT
+    let monkeys = demo_monkeys();
+    println!(
+        "PART 2 {}",
+        parts(monkeys, 1..=10_000, ManagementStrategy::Span)
+    );
+}
+
+fn parts(
+    mut monkeys: Vec<Monkey>,
+    range: RangeInclusive<i32>,
+    management_strategy: ManagementStrategy,
+) -> usize {
+    let modulo_span = monkeys.iter().map(|m| m.test_divisor).product::<u64>();
+
+    for _ in range {
+        for m_i in 0..monkeys.len() {
+            let items_len = monkeys.get(m_i).unwrap().items.len();
+            for i in (0..items_len).rev() {
+                let monkey = monkeys.get_mut(m_i).unwrap();
+
+                monkey.inspections += 1;
+                let item = monkey.items.get_mut(i).unwrap();
+                // ALL THE test_divisor SPAN modulo_span.
+                // WE CAN MANAGE WORRIED LEVELS BY KEEPING IT IN modulo_span
+                // WHICH AVOIDS NUMBERS GETTING TOO LARGE.
+                *item = (monkey.operation)(*item);
+                match management_strategy {
+                    ManagementStrategy::Div3 => *item /= 3,
+                    ManagementStrategy::Span => *item %= modulo_span,
+                };
+
+                let throw_monkey_i = if *item % monkey.test_divisor == 0 {
+                    monkey.throw_true
+                } else {
+                    monkey.throw_false
+                };
+
+                let throw_item = monkey.items.swap_remove(i);
+                let throw_monkey = monkeys.get_mut(throw_monkey_i).unwrap();
+                throw_monkey.items.push(throw_item);
+                // println!("THROW {} FROM {} TO {}", throw_item, m_i, throw_monkey_i);
+            }
+        }
+        //     for monkey in monkeys.iter() {
+        //         println!(
+        //             "{}",
+        //             monkey
+        //                 .items
+        //                 .iter()
+        //                 .map(|x| x.to_string() + ",")
+        //                 .collect::<String>()
+        //         )
+        //     }
+    }
+    return get_monkey_business(&monkeys);
+}
+
+fn get_monkey_business(monkeys: &Vec<Monkey>) -> usize {
+    let mut monkey_inspections = monkeys
+        .iter()
+        .map(|x| x.inspections)
+        .collect::<Vec<usize>>();
+
+    monkey_inspections.sort_by(|a, b| b.cmp(a));
+    return monkey_inspections.get(0).unwrap() * monkey_inspections.get(1).unwrap();
+}
+
+// COULDN'T BE BOTHERED TO WRITE A PARSER FOR THIS DATA
+// FORMATTED IT USING VSCODE MULTICURSORS
+fn demo_monkeys() -> Vec<Monkey> {
+    let mut monkeys = Vec::<Monkey>::new();
+    monkeys.push(Monkey {
+        items: vec![79, 98],
+        operation: |old: u64| old * 19,
+        test_divisor: 23,
+        throw_true: 2,
+        throw_false: 3,
+        inspections: 0,
+    });
+
+    monkeys.push(Monkey {
+        items: vec![54, 65, 75, 74],
+        operation: |old: u64| old + 6,
+        test_divisor: 19,
+        throw_true: 2,
+        throw_false: 0,
+        inspections: 0,
+    });
+
+    monkeys.push(Monkey {
+        items: vec![79, 60, 97],
+        operation: |old: u64| old * old,
+        test_divisor: 13,
+        throw_true: 1,
+        throw_false: 3,
+        inspections: 0,
+    });
+
+    monkeys.push(Monkey {
+        items: vec![74],
+        operation: |old: u64| old + 3,
+        test_divisor: 17,
+        throw_true: 0,
+        throw_false: 1,
+        inspections: 0,
+    });
+    return monkeys;
+}
+
+fn input_monkeys() -> Vec<Monkey> {
+    let mut monkeys = Vec::<Monkey>::new();
+    monkeys.push(Monkey {
+        items: vec![84, 66, 62, 69, 88, 91, 91],
+        operation: |old: u64| old * 11,
+        test_divisor: 2,
+        throw_true: 4,
+        throw_false: 7,
+        inspections: 0,
+    });
+    monkeys.push(Monkey {
+        items: vec![98, 50, 76, 99],
+        operation: |old: u64| old * old,
+        test_divisor: 7,
+        throw_true: 3,
+        throw_false: 6,
+        inspections: 0,
+    });
+    monkeys.push(Monkey {
+        items: vec![72, 56, 94],
+        operation: |old: u64| old + 1,
+        test_divisor: 13,
+        throw_true: 4,
+        throw_false: 0,
+        inspections: 0,
+    });
+    monkeys.push(Monkey {
+        items: vec![55, 88, 90, 77, 60, 67],
+        operation: |old: u64| old + 2,
+        test_divisor: 3,
+        throw_true: 6,
+        throw_false: 5,
+        inspections: 0,
+    });
+    monkeys.push(Monkey {
+        items: vec![69, 72, 63, 60, 72, 52, 63, 78],
+        operation: |old: u64| old * 13,
+        test_divisor: 19,
+        throw_true: 1,
+        throw_false: 7,
+        inspections: 0,
+    });
+    monkeys.push(Monkey {
+        items: vec![89, 73],
+        operation: |old: u64| old + 5,
+        test_divisor: 17,
+        throw_true: 2,
+        throw_false: 0,
+        inspections: 0,
+    });
+    monkeys.push(Monkey {
+        items: vec![78, 68, 98, 88, 66],
+        operation: |old: u64| old + 6,
+        test_divisor: 11,
+        throw_true: 2,
+        throw_false: 5,
+        inspections: 0,
+    });
+    monkeys.push(Monkey {
+        items: vec![70],
+        operation: |old: u64| old + 7,
+        test_divisor: 5,
+        throw_true: 1,
+        throw_false: 3,
+        inspections: 0,
+    });
+    return monkeys;
 }