Did day 11 problem 1.

input/11.txt

@@ -0,0 +1,55 @@
+Monkey 0:
+  Starting items: 89, 95, 92, 64, 87, 68
+  Operation: new = old * 11
+  Test: divisible by 2
+    If true: throw to monkey 7
+    If false: throw to monkey 4
+
+Monkey 1:
+  Starting items: 87, 67
+  Operation: new = old + 1
+  Test: divisible by 13
+    If true: throw to monkey 3
+    If false: throw to monkey 6
+
+Monkey 2:
+  Starting items: 95, 79, 92, 82, 60
+  Operation: new = old + 6
+  Test: divisible by 3
+    If true: throw to monkey 1
+    If false: throw to monkey 6
+
+Monkey 3:
+  Starting items: 67, 97, 56
+  Operation: new = old * old
+  Test: divisible by 17
+    If true: throw to monkey 7
+    If false: throw to monkey 0
+
+Monkey 4:
+  Starting items: 80, 68, 87, 94, 61, 59, 50, 68
+  Operation: new = old * 7
+  Test: divisible by 19
+    If true: throw to monkey 5
+    If false: throw to monkey 2
+
+Monkey 5:
+  Starting items: 73, 51, 76, 59
+  Operation: new = old + 8
+  Test: divisible by 7
+    If true: throw to monkey 2
+    If false: throw to monkey 1
+
+Monkey 6:
+  Starting items: 92
+  Operation: new = old + 5
+  Test: divisible by 11
+    If true: throw to monkey 3
+    If false: throw to monkey 0
+
+Monkey 7:
+  Starting items: 99, 76, 78, 76, 79, 90, 89
+  Operation: new = old + 7
+  Test: divisible by 5
+    If true: throw to monkey 4
+    If false: throw to monkey 5

input/11sample.txt

@@ -0,0 +1,27 @@
+Monkey 0:
+  Starting items: 79, 98
+  Operation: new = old * 19
+  Test: divisible by 23
+    If true: throw to monkey 2
+    If false: throw to monkey 3
+
+Monkey 1:
+  Starting items: 54, 65, 75, 74
+  Operation: new = old + 6
+  Test: divisible by 19
+    If true: throw to monkey 2
+    If false: throw to monkey 0
+
+Monkey 2:
+  Starting items: 79, 60, 97
+  Operation: new = old * old
+  Test: divisible by 13
+    If true: throw to monkey 1
+    If false: throw to monkey 3
+
+Monkey 3:
+  Starting items: 74
+  Operation: new = old + 3
+  Test: divisible by 17
+    If true: throw to monkey 0
+    If false: throw to monkey 1

src/s11a.d

@@ -0,0 +1,57 @@
+module s11a;
+import util;
+
+void main() {
+    Monkey[] monkeys = readText("input/11.txt").strip.splitter("\n\n")
+        .map!(parseMonkey).array;
+    
+    for (int i = 0; i < 20; i++) {
+        for (int mId = 0; mId < monkeys.length; mId++) {
+            Monkey* m = &monkeys[mId];
+            while (m.items.length > 0) {
+                int item = m.items[0];
+                m.items = m.items.remove(0);
+                
+                char op = m.operation[0];
+                string argS = m.operation[1];
+                int arg = argS == "old" ? item : argS.to!int;
+                int newValue;
+                if (op == '+') newValue = item + arg;
+                if (op == '*') newValue = item * arg;
+
+                newValue /= 3;
+
+                if (newValue % m.testDivisor == 0) {
+                    monkeys[m.testTrueMonkeyId].items ~= newValue;
+                } else {
+                    monkeys[m.testFalseMonkeyId].items ~= newValue;
+                }
+                m.inspections++;
+            }
+        }
+    }
+
+    int[] topValues = monkeys.map!(m => m.inspections).array.topN!"a > b"(2);
+    int monkeyBusiness = reduce!"a * b"(1, topValues);
+    writeln(monkeyBusiness);
+}
+
+struct Monkey {
+    int[] items;
+    Tuple!(char, string) operation;
+    int testDivisor;
+    int testTrueMonkeyId;
+    int testFalseMonkeyId;
+    int inspections;
+}
+
+Monkey parseMonkey(string s) {
+    string[] lines = s.splitter("\n").array;
+    Monkey m;
+    m.items = lines[1][18..$].splitter(", ").map!(s => s.to!int).array;
+    m.operation = Tuple!(char, string)(lines[2][23], lines[2][25..$]);
+    m.testDivisor = lines[3][21..$].to!int;
+    m.testTrueMonkeyId = lines[4][29..$].to!int;
+    m.testFalseMonkeyId = lines[5][30..$].to!int;
+    return m;
+}

src/s11b.d

@@ -0,0 +1,65 @@
+module s11a;
+import util;
+
+import std.bigint;
+
+void main() {
+    Monkey[] monkeys = readText("input/11sample.txt").strip.splitter("\n\n")
+        .map!(parseMonkey).array;
+    
+    for (int i = 0; i < 10_000; i++) {
+        writefln!"Round %d"(i + 1);
+        for (int mId = 0; mId < monkeys.length; mId++) {
+            Monkey* m = &monkeys[mId];
+            while (m.items.length > 0) {
+                BigInt item = m.items[0];
+                m.items = m.items.remove(0);
+                
+                char op = m.operation[0];
+                string argS = m.operation[1];
+                BigInt arg = argS == "old" ? item : argS.to!BigInt;
+                BigInt newValue;
+                if (op == '+') newValue = item + arg;
+                if (op == '*') newValue = item * arg;
+
+                if (newValue % m.testDivisor == 0) {
+                    monkeys[m.testTrueMonkeyId].items ~= newValue;
+                } else {
+                    monkeys[m.testFalseMonkeyId].items ~= newValue;
+                }
+                m.inspections++;
+            }
+        }
+        if ((i + 1) % 1000 == 0) {
+            writefln!"== After round %d =="(i + 1);
+            for (int mId = 0; mId < monkeys.length; mId++) {
+                writefln!"Monkey %d inspected items %d times."(mId, monkeys[mId].inspections);
+                writeln(monkeys[mId].items);
+            }
+        }
+    }
+
+    ulong[] topValues = monkeys.map!(m => m.inspections).array.topN!"a > b"(2UL);
+    ulong monkeyBusiness = reduce!"a * b"(1UL, topValues);
+    writeln(monkeyBusiness);
+}
+
+struct Monkey {
+    BigInt[] items;
+    Tuple!(char, string) operation;
+    int testDivisor;
+    int testTrueMonkeyId;
+    int testFalseMonkeyId;
+    ulong inspections;
+}
+
+Monkey parseMonkey(string s) {
+    string[] lines = s.splitter("\n").array;
+    Monkey m;
+    m.items = lines[1][18..$].splitter(", ").map!(s => s.to!BigInt).array;
+    m.operation = Tuple!(char, string)(lines[2][23], lines[2][25..$]);
+    m.testDivisor = lines[3][21..$].to!int;
+    m.testTrueMonkeyId = lines[4][29..$].to!int;
+    m.testFalseMonkeyId = lines[5][30..$].to!int;
+    return m;
+}

src/util.d

@@ -13,6 +13,7 @@ public import std.uni;
 public import std.array;
 public import std.format;
 public import std.math;
+public import std.typecons;
 
 /** 
  * Simple set implementation since the stdlib doesn't really have a good one.