2022 day 11 part 1

lachlanroche · lachlanroche · commit e85dfdf0b0df · 2022-12-11T15:43:22.000+10:00
diff --git a/aoc22.playground/Pages/Day11.xcplaygroundpage/Contents.swift b/aoc22.playground/Pages/Day11.xcplaygroundpage/Contents.swift
@@ -0,0 +1,7 @@
+//: [Previous](@previous)
+
+import Foundation
+
+part1()
+
+//: [Next](@next)
diff --git a/aoc22.playground/Pages/Day11.xcplaygroundpage/Resources/input.txt b/aoc22.playground/Pages/Day11.xcplaygroundpage/Resources/input.txt
@@ -0,0 +1,55 @@
+Monkey 0:
+  Starting items: 76, 88, 96, 97, 58, 61, 67
+  Operation: new = old * 19
+  Test: divisible by 3
+    If true: throw to monkey 2
+    If false: throw to monkey 3
+
+Monkey 1:
+  Starting items: 93, 71, 79, 83, 69, 70, 94, 98
+  Operation: new = old + 8
+  Test: divisible by 11
+    If true: throw to monkey 5
+    If false: throw to monkey 6
+
+Monkey 2:
+  Starting items: 50, 74, 67, 92, 61, 76
+  Operation: new = old * 13
+  Test: divisible by 19
+    If true: throw to monkey 3
+    If false: throw to monkey 1
+
+Monkey 3:
+  Starting items: 76, 92
+  Operation: new = old + 6
+  Test: divisible by 5
+    If true: throw to monkey 1
+    If false: throw to monkey 6
+
+Monkey 4:
+  Starting items: 74, 94, 55, 87, 62
+  Operation: new = old + 5
+  Test: divisible by 2
+    If true: throw to monkey 2
+    If false: throw to monkey 0
+
+Monkey 5:
+  Starting items: 59, 62, 53, 62
+  Operation: new = old * old
+  Test: divisible by 7
+    If true: throw to monkey 4
+    If false: throw to monkey 7
+
+Monkey 6:
+  Starting items: 62
+  Operation: new = old + 2
+  Test: divisible by 17
+    If true: throw to monkey 5
+    If false: throw to monkey 7
+
+Monkey 7:
+  Starting items: 85, 54, 53
+  Operation: new = old + 3
+  Test: divisible by 13
+    If true: throw to monkey 4
+    If false: throw to monkey 0
diff --git a/aoc22.playground/Pages/Day11.xcplaygroundpage/Sources/Day11.swift b/aoc22.playground/Pages/Day11.xcplaygroundpage/Sources/Day11.swift
@@ -0,0 +1,92 @@
+import Foundation
+
+enum Operation {
+    case plus
+    case multiply
+    case square
+    
+    func apply(worry: Int, constant: Int) -> Int {
+        switch self {
+        case .plus:
+            return worry + constant
+        case .multiply:
+            return worry * constant
+        case .square:
+            return worry * worry
+        }
+    }
+}
+
+struct Monkey {
+    let id: Int
+    var items: [Int]
+    let op: Operation
+    let constant: Int
+    let divisible: Int
+    let ifTrue: Int
+    let ifFalse: Int
+    var inspections = 0
+}
+
+public func part1() -> Int {
+    var monkeys = [Monkey]()
+    var id = 0
+    var items = [Int]()
+    var op = Operation.plus
+    var constant = 0
+    var divisible = 0
+    var ifTrue = 0
+    var ifFalse = 0
+    for line in stringsFromFile() {
+        if line.hasPrefix("Monkey ") {
+            id = Int(line.replacingOccurrences(of: ":", with: "").split(separator: " ").last!)!
+        } else if line.hasPrefix("  Starting items:") {
+            items = line.replacingOccurrences(of: ", ", with: " ").split(separator: " ").dropFirst(2).compactMap { Int($0)! }
+        } else if line.hasPrefix("  Operation") {
+            if line.contains("old * old") {
+                op = .square
+                constant = 1
+            } else {
+                constant = Int(line.split(separator: " ").last!)!
+                op = line.contains("old + ") ? .plus : .multiply
+            }
+        } else if line.hasPrefix("  Test") {
+            divisible = Int(line.split(separator: " ").last!)!
+        } else if line.hasPrefix("    If true") {
+            ifTrue = Int(line.split(separator: " ").last!)!
+        } else if line.hasPrefix("    If false") {
+            ifFalse = Int(line.split(separator: " ").last!)!
+            monkeys.append(Monkey(id: id, items: items, op: op, constant: constant, divisible: divisible, ifTrue: ifTrue, ifFalse: ifFalse))
+        }
+    }
+    
+    func inspect(monkey id: Int) {
+        let items = monkeys[id].items
+        monkeys[id].items = []
+        for item in items {
+            var worry = item
+            worry = monkeys[id].op.apply(worry: worry, constant: monkeys[id].constant)
+            worry /= 3
+            if worry % monkeys[id].divisible == 0 {
+                monkeys[monkeys[id].ifTrue].items.append(worry)
+            } else {
+                monkeys[monkeys[id].ifFalse].items.append(worry)
+            }
+            monkeys[id].inspections += 1
+        }
+    }
+    
+    for _ in 0..<20 {
+        for i in 0..<(monkeys.count) {
+            inspect(monkey: i)
+        }
+    }
+    
+    monkeys.sort { $0.inspections > $1.inspections }
+    
+    return monkeys[0].inspections * monkeys[1].inspections
+}
+
+public func part2() -> Int {
+    0
+}
diff --git a/aoc22.playground/contents.xcplayground b/aoc22.playground/contents.xcplayground
@@ -11,5 +11,6 @@
         <page name='Day08'/>
         <page name='Day09'/>
         <page name='Day10'/>
+        <page name='Day11'/>
     </pages>
 </playground>
