Advent of Code 2020: Python Solution Day 16

rules = [] my_ticket = [] nearby_ticket = [] tickets = [] temp = [] for i, line in enumerate(lines): if line != "\n": temp.append(line.rstrip()) elif line == "\n": if len(rules) == 0: rules = temp rule = {v.split(": ")[0]: v.split(": ")[1].split(" or ") for v in rules} rules = {} for k,v in rule.items(): v = [list(range(int(i.split("-")[0]), int(i.split("-")[1])+1)) for i in v] v = [i for k in v for i in k] rules[k] = v temp = [] if len(my_ticket) == 0: my_ticket = temp temp = [] if len(nearby_ticket) == 0: nearby_ticket = temp nt = [v.split(",") for v in nearby_ticket[1:]] nt = [int(i) for j in nt for i in j] nearby_ticket = nt mint = lambda l: [int(i) for i in l.split(",")] tickets = [mint(j) for j in temp[1:]] error_counts = 0 valid_tickets = [] for values in tickets: for v in values: valid = False for rv in rules.values(): if v in rv: valid = True break if not valid: error_counts += v break if valid: valid_tickets.append(values) print(f"Error Rate: {error_counts}.") # a dictionary to hold possible fields for each col possible_fields = {i: set(rules.keys()) for i in range(len(valid_tickets[0]))} for ticket in valid_tickets: for i, value in enumerate(ticket): for field in rules: possible = False if value in rules[field]: possible = True if not possible: possible_fields[i].discard(field) # remove repeated fields for i in sorted(possible_fields, key=lambda k: len(possible_fields[k])): this_field = next(iter(possible_fields[i])) for j in possible_fields: if i != j: possible_fields[j].discard(this_field) mt = [int(x) for x in lines[22].split(",")] ans = 1 for i in possible_fields: if possible_fields[i].pop().startswith("departure"): ans *= mt[i] print("Part 1:", error_counts) print("Part 2:", ans)