Carré de Polybe

decodage.py

# -*- coding: utf-8 -*-

M = [["A", "B", "C", "D",  "E"],
     ["F", "G", "H", "IJ", "K"],
     ["L", "M", "N", "O",  "P"],
     ["Q", "R", "S", "T",  "U"],
     ["V", "W", "X", "Y",  "Z"]]


def decode(texte):
    for lettre in texte.split():
        if len(lettre) != 2 or not lettre.isdigit() or \
                int(lettre) > 55 or int(lettre) < 11:
            raise ValueError(lettre)

        x, y = [u - 1 for u in map(int, lettre)]
        print M[x][y]


texte = raw_input("Tapez le texte à décoder:  ")
decode(texte)