efrei/theorie-graphes/calcul_rang.py

#!/usr/bin/env python3

"""Algorithme de calcul de rang"""

import pprint


def main() -> None:
    """Algorithme itératif de calcul de rang sur une matrice d'adjacence"""

    rangs = []

    matrice = [
        [0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0],
        [0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1],
        [0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0],
        [0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1],
        [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
        [1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0],
        [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1],
        [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
        [0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0],
        [0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0],
        [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
        [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    ]

    print("Matrice :")
    pprint.pprint(matrice)

    for _ in range(len(matrice)):
        d_entrant = [0] * len(matrice)

        for line in matrice:
            for i, row in enumerate(line):
                d_entrant[i] += row

        to_remove = [i for i, d in enumerate(d_entrant) if d == 0]
        if not to_remove:
            break

        for i in reversed(to_remove):
            matrice.pop(i)
        for i in reversed(to_remove):
            for line in matrice:
                line.pop(i)

        rangs.append(to_remove)

    for rang, sommets in enumerate(rangs):
        print(f"Rang {rang} :")
        print(f"  {sommets}")


if __name__ == "__main__":
    main()