chopin.py

# https://icpc.kattis.com/problems/chopin

import sys


EXCEPTIONS = ('Ab minor', 'D# major', 'A# major', 'D# minor', 'A# minor', 'Gb major', 'C# major', 'Gb minor', 'Db minor', 'G# major')

inverse = lambda x: {'b': '#', '#': 'b'}[x]
alternate = lambda scale: '{0}{1}'.format(chr((((ord(scale[0]) + {'b': -1, '#': 1}[scale[1]]) - 65) % 7) + 65), inverse(scale[1]))

def translate(note):
    scale, tone = note.split()
    if len(scale) == 1:
        return 'UNIQUE'

    out = '{0} {1}'.format(alternate(scale), tone)
    if out in EXCEPTIONS:
        return note
    return out


if __name__ == '__main__':
    with open(sys.argv[1]) as f:
        for number, line in enumerate(f):
            print 'Case {0}: {1}'.format(number + 1, translate(line))

input.txt

Ab minor
D# major
G minor

output.txt

Case 1: G# minor
Case 2: Eb major
Case 3: UNIQUE