day 11 python slight optimization

day11/input

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+Monkey 0:
+  Starting items: 93, 54, 69, 66, 71
+  Operation: new = old * 3
+  Test: divisible by 7
+    If true: throw to monkey 7
+    If false: throw to monkey 1
+
+Monkey 1:
+  Starting items: 89, 51, 80, 66
+  Operation: new = old * 17
+  Test: divisible by 19
+    If true: throw to monkey 5
+    If false: throw to monkey 7
+
+Monkey 2:
+  Starting items: 90, 92, 63, 91, 96, 63, 64
+  Operation: new = old + 1
+  Test: divisible by 13
+    If true: throw to monkey 4
+    If false: throw to monkey 3
+
+Monkey 3:
+  Starting items: 65, 77
+  Operation: new = old + 2
+  Test: divisible by 3
+    If true: throw to monkey 4
+    If false: throw to monkey 6
+
+Monkey 4:
+  Starting items: 76, 68, 94
+  Operation: new = old * old
+  Test: divisible by 2
+    If true: throw to monkey 0
+    If false: throw to monkey 6
+
+Monkey 5:
+  Starting items: 86, 65, 66, 97, 73, 83
+  Operation: new = old + 8
+  Test: divisible by 11
+    If true: throw to monkey 2
+    If false: throw to monkey 3
+
+Monkey 6:
+  Starting items: 78
+  Operation: new = old + 6
+  Test: divisible by 17
+    If true: throw to monkey 0
+    If false: throw to monkey 1
+
+Monkey 7:
+  Starting items: 89, 57, 59, 61, 87, 55, 55, 88
+  Operation: new = old + 7
+  Test: divisible by 5
+    If true: throw to monkey 2
+    If false: throw to monkey 5

day11/sample

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+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

day11/sol.py

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+from collections import namedtuple
+from copy import deepcopy
+import math
+
+Monkey = namedtuple('Monkey', 'index, op, divisor, target')
+def parse(input):
+    monkeys = []
+    items = {}
+    for i, chunk in enumerate(input.split("\n\n")):
+        lines = chunk.strip().split("\n")
+        assert 'Starting items:' in lines[1]
+        assert 'Operation: new =' in lines[2]
+        assert 'Test: divisible by' in lines[3]
+        assert 'If true: throw to' in lines[4]
+        assert 'If false: throw to' in lines[5]
+
+        items[i] = [int(x.strip()) for x in lines[1].split(":")[1].split(",")]
+        op = eval("lambda old: " + lines[2].split("=")[1])
+        divisor = int(lines[3].split()[-1])
+        target = [
+            int(lines[5].split()[-1]),
+            int(lines[4].split()[-1]),
+        ]
+        monkeys.append(Monkey(i, op, divisor, target))
+    return monkeys, items
+
+def play(monkeys, items, rounds=1, N=None):
+    throws = {m.index: 0 for m in monkeys}
+    for _ in range(rounds):
+        for m in monkeys:
+            for x in items[m.index]:
+                if N:
+                    nx = m.op(x) % N
+                else:
+                    nx = m.op(x) // 3
+                trg = m.target[nx % m.divisor == 0]
+                #print(f'{i}: {x} -> {nx}. throwing to {trg}')
+                items[trg].append(nx)
+            throws[m.index] += len(items[m.index])
+            items[m.index] = []
+    show(items)
+    return throws
+
+def show(items):
+    for k in items:
+        print(k, items[k])
+
+def monkeybusiness(throws):
+    a, b = sorted(throws.values())[-2:]
+    return a*b
+
+def lcm(ints):
+    n = 1
+    for x in ints:
+        n *= x // math.gcd(n, x)
+    return n
+
+def main():
+    monkeys, items = parse(open("input").read())
+    #print(monkeys)
+    show(items)
+
+    throws = play(monkeys, deepcopy(items), rounds=20)
+    print(monkeybusiness(throws))
+
+    N = lcm(m.divisor for m in monkeys)
+    throws = play(monkeys, deepcopy(items), rounds=10000, N=N)
+    print(monkeybusiness(throws))
+
+main()