My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2023/15
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2023/day15.py
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2023/day15.py
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import fileinput
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from collections import defaultdict
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def HASH(code):
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val = 0
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for c in code:
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val += ord(c)
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val *= 17
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val %= 256
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return val
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# Parse problem input.
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STEPS = next(fileinput.input()).strip().split(',')
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# Solve part 1.
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print("Part 1:", sum(HASH(step) for step in STEPS))
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# Solve part 2.
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BOXES = defaultdict(list)
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for step in STEPS:
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if step[-1] == '-':
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label = step[:-1]
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box = HASH(label)
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BOXES[box] = [lens for lens in BOXES[box] if lens[0] != label]
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else:
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focal = int(step[-1])
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label = step[:-2]
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box = HASH(label)
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for i, (other_label, other_focal) in enumerate(BOXES[box]):
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if other_label == label:
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BOXES[box][i] = (label, focal)
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break
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else:
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BOXES[box].append((label, focal))
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lenses = {}
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for box_num, box in BOXES.items():
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for slot_num, (label, focal) in enumerate(box, start=1):
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lenses[label] = (box_num + 1) * slot_num * focal
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print("Part 2:", sum(lenses.values()))