codeforces - 1 - B (py)

B.py

#!/usr/bin/env python
"""(c) gorlum0 [at] gmail.com"""
import re
import string
from math import log
from sys import stdin

def int2base(x, base, digits = '0123456789abcdefghijklmnopqrstuvwxyz'):
    '''inverse of int(x, base), 2 <= base <= 36'''
    if x < 0:
        sign = -1
    elif x==0:
        return '0'
    else:
        sign = 1

    x *= sign
    number = []
    while x:
        number.append(digits[x % base])
        x /= base
    if sign < 0:
        number.append('-')
    number.reverse()
    return ''.join(number)

def sum_geom(b1, q, n):
    return b1 * (q**n - 1) // (q - 1)

def main():
    trantab1 = string.maketrans(
                (string.digits + string.lowercase)[:26],
                string.uppercase)
    trantab2 = string.maketrans(
                string.uppercase,
                (string.digits + string.lowercase)[:26])

    t = int(stdin.readline())
    for line in stdin:
        # exclusive
        m1 = re.match(r'\s*R(\d+)C(\d+)\s*$', line)
        m2 = re.match(r'\s*([A-Z]+)([0-9]+)\s*$', line)

        if m1:
            r, c = m1.groups()
            c = int(c) - 1
            k = int(log(25*c + 1, 26))
            c -= sum_geom(1, 26, k) - 1

            c = int2base(c, 26)
            c = c.translate(trantab1)

            print '%s%s' % (c.rjust(k, 'A'), r)

        if m2:
            c, r = m2.groups()
            c = c.translate(trantab2)
            c = int(c, 26) + 1 + sum_geom(1, 26, len(c)) - 1

            print 'R%sC%d' % (r, c)

if __name__ == '__main__':
    main()