75 lines
2.2 KiB
Python
75 lines
2.2 KiB
Python
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from copy import deepcopy
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from collections import defaultdict
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from output import ints
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def solve(data):
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M = []
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for md in data.split("\n\n"):
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m = {}
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starting_items, operation, divisor, if_true, if_false = md.splitlines()[1:]
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m["items"] = ints(starting_items)
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m["if_false"] = ints(if_false)[0]
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m["if_true"] = ints(if_true)[0]
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m["divisor"] = ints(divisor)[0]
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m["operation_values"] = operation.split()[-3:]
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M.append(m)
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p12 = []
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# Part 2 resolver.
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#
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# Not sure what to call this, so I go for Greatest Common
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# Divisor. Had to look for hints at subreddit to find it out.
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# It basically fasten up the computation speed by keeping
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# the numbers low.
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#
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# Apparently, this is common Modular arithmetic:
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# https://en.wikipedia.org/wiki/Modular_arithmetic
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gcd = 1
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for d in [m["divisor"] for m in M]:
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gcd *= d
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for rounds, wld in [(20, True), (10_000, False)]:
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B = defaultdict(int)
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MM = deepcopy(M)
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for _ in range(rounds):
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for i, m in enumerate(MM):
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while m["items"]:
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wl = m["items"].pop(0)
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B[i] += 1
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x, y, z = m["operation_values"]
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x = int(wl) if x == "old" else int(x)
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z = int(wl) if z == "old" else int(z)
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match y:
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case "+":
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wl = x + z
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case "*":
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wl = x * z
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if wld:
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wl = wl // 3
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else:
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wl = wl % gcd
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if wl % m["divisor"] == 0:
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MM[m["if_true"]]["items"].append(wl)
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else:
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MM[m["if_false"]]["items"].append(wl)
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a, b, *_ = sorted(B.values(), reverse=True)
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p12.append(a * b)
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p1, p2 = p12
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return p1, p2
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def _state(M):
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return tuple([(tuple(m["items"])) for m in M])
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if __name__ == "__main__":
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with open("./input/11.txt", "r") as f:
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inp = f.read().strip()
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p1, p2 = solve(inp)
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print(p1)
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print(p2)
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assert p1 == 50616
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assert p2 == 11309046332
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