39 lines
1.6 KiB
Python
39 lines
1.6 KiB
Python
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with open('input16', 'r') as file:
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input = [ls.strip().split('\n') for ls in file.read().strip().split('\n\n')]
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import re
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fieldregex = re.compile(r'([\w ]+): (\d+)-(\d+) or (\d+)-(\d+)')
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ex_fields = lambda x: (x[0], [int(i) for i in x[1:]])
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fields = dict(ex_fields(fieldregex.match(line).groups()) for line in input[0])
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my_ticket = [int(x) for x in input[1][1].split(',')]
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nearby_tickets = [[int(x) for x in line.split(',')] for line in input[2][1:]]
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fieldfuncs = {k:(lambda x, v=v: (v[0]<=x<=v[1]) or (v[2]<=x<=v[3])) for k,v in fields.items()}
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any_valid = lambda x: any([f(x) for f in fieldfuncs.values()])
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print(f'Part 1: error sum = {sum([sum([x for x in ticket if not any_valid(x)]) for ticket in nearby_tickets])}')
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valid_tickets = [ticket for ticket in nearby_tickets if all([any_valid(x) for x in ticket])]
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confirmed_fields = {}
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potential_fields = {i:set(fields.keys()) for i in range(len(fields))}
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def sweep():
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for ticket in valid_tickets:
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for i,keys in list(potential_fields.items()): # We mutate the dict as we iterate
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for key in list(keys): # We mutate the set as we iterate
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if i in potential_fields:
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if not fieldfuncs[key](ticket[i]):
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potential_fields[i].remove(key)
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if len(potential_fields[i]) == 1:
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c_key = potential_fields.pop(i).pop()
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confirmed_fields[c_key] = i
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for vset in potential_fields.values():
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vset.remove(c_key)
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while len(potential_fields) > 0:
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sweep()
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from math import prod # lmao
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print(f'Part 2: {prod([my_ticket[i] for key,i in confirmed_fields.items() if key.startswith("departure")])}')
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