Advent of code 2020-12-05

#   Advent of code 2020-12-05
#   Armandur


rows = list(range(0, 128))
columns = list(range(0, 8))


def search(entry, seats):
    if len(seats) > 1:
        half = int(len(seats) / 2)
        if entry[0] == "F" or entry[0] == "L":
            return search(entry[1:], seats[:half])  # Keep first half, and run func again without first char in entry

        elif entry[0] == "B" or entry[0] == "R":
            return search(entry[1:], seats[half:])  # Keep second half, and run func again without first char in entry
    else:
        return seats[0]                             # Only one element remaining


seatIDs = []
with open("5 - input", 'r') as file:
    lines = file.readlines()
    for line in lines:
        row = search(line[:7], rows)        # Search for row with first 7 chars of the line/entry
        column = search(line[7:], columns)  # Search for column with the last chars after first 7
        seatIDs.append((row * 8) + column)  # Calculate and append ID to list

seatIDs.sort()      # Sort IDs in numerical order
print(seatIDs[-1])  # Part 1 - Print the last ID in list, which will be the highest

#   Part 2 - One ID is missing, check all IDs in incremental order, check if the current seatID is equal to the last+1,
#   if not it is missing.

last = seatIDs[0] - 1
for seatID in seatIDs:
    if seatID != last + 1:
        print(seatID - 1)
        break
    last = seatID