My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2022/21
+56
+56
2022/day21.py
+56
2022/day21.py
···
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import copy
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import fileinput
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from collections import defaultdict
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from utils import topsort
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GRAPH = defaultdict(set)
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YELLS = {}
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for line in fileinput.input():
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monkey, rest = line.strip().split(': ')
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if rest.isnumeric():
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YELLS[monkey] = int(rest)
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else:
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d1, op, d2 = rest.split(' ')
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YELLS[monkey] = (d1, op, d2)
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GRAPH[monkey].add(d1)
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GRAPH[monkey].add(d2)
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ORDERING = list(reversed(topsort(GRAPH)))
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def simulate(yells, humn=None):
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if humn:
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yells['humn'] = humn
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d1, _, d2 = yells['root']
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yells['root'] = (d1, "==", d2)
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for monkey in ORDERING:
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if type(yells[monkey]) != int:
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d1, op, d2 = yells[monkey]
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yells[monkey] = eval(f"{yells[d1]} {op} {yells[d2]}")
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return int(yells['root'])
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print("Part 1:", simulate(copy.deepcopy(YELLS)))
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# For my problem input, we analyze some values of the two monkeys that
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# the `root` monkey depends on, and how it changes depends on `humn`.
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#
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# humn=3 d1=72750855862944 d2=31522134274080
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# humn=8 d1=72750855862880 d2=31522134274080
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#
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# When `humn` increases by 5, `d1` decreases by 64, and `d2` is constant.
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# Therefore, we need to solve the following equation:
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#
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# humn = 3 + (72750855862944 - 31522134274080) * (5 / 64)
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# = 3220993874133
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HUMN = 3220993874133
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part_2 = simulate(copy.deepcopy(YELLS), humn=HUMN); assert part_2 == 1
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print("Part 2:", HUMN)
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