pyBoardingList

# Arrange a boarding list for passengers on a plane, starting from the rear (higher row numbers)
# and boarding window seats (A and D) infront of aisle seats (B and C)

inlist = ["8A", "2B", "6D", "4C", "1B", "7C", "10B", "6A", "8C", "11A", "9B", "6B"]

outlist = []
for s in inlist:
    # Create a value which represents the seat's distance from the aisle
    vs = str(abs(ord(s[-1]) - 66.5))
    # ord("A") = 65, so 'A' produces 1.5
    # ord('B') = 66, so 'B' produces 0.5
    # ord('C') = 67, so 'C' produces 0.5
    # ord('D') = 68, so 'D' produces 1.5
    # So when sorted in reverse, A and D come before B and C

    # Create a list containing seat number (with leading zero if needed) concatenated with aisle distance,
    # Followed by the original seat code as a second entry per tuple
    outlist.append((s[:-1].zfill(2) + vs, s) )

# Sort the resultant list in reverse, and then print the original seat code for each list entry
for tup in sorted(outlist, reverse=True):
    print(tup[1], end="  ")
print()

# Output:
# 11A  10B  9B  8A  8C  7C  6D  6A  6B  4C  2B  1B