#!/usr/bin/env python3

"""Algorithme d'Euclide

Calcule le PGCD de deux nombres.
"""

import sys


def main():
    if len(sys.argv) == 3:
        a = int(sys.argv[1])
        b = int(sys.argv[2])
    else:
        a = int(input("a : "))
        b = int(input("b : "))

    calculate(a, b)


def calculate(a, b):

    # Initialisation
    r = ["r", a % b]
    a = ["a", a]
    b = ["b", b]

    # Séquence
    while True:
        a.append(b[-1])
        b.append(r[-1])
        r.append(a[-1] % b[-1])
        if r[-1] == 0:
            break

    print_table(a, b, r)
    print("Le PGCD est", r[-2])


def print_table(a, b, r):
    """Représentation de l'algorithme"""

    width = max((len(str(i)) for i in r))

    for i in range(len(r)):
        print(f"{a[i]:^{width}}  {b[i]:^{width}}  {r[i]:^{width}}")


if __name__ == "__main__":
    main()