# know what is Pigeonhole_principle
# https://www.youtube.com/watch?v=IeTLZPNIPJQ


def pigeonhole_sort(a):

    # (number of pigeonholes we need)
    my_min = min(a)
    my_max = max(a)
    size = my_max - my_min + 1

    # total pigeonholes
    holes = [0] * size

    # filling up the pigeonholes.
    for x in a:
        holes[x - my_min] += 1

    # Put the elements back into the array in order.
    i = 0
    for count in range(size):
        while holes[count] > 0:
            holes[count] -= 1
            a[i] = count + my_min
            i += 1


a = [10, 3, 2, 7, 4, 6, 8]

# list only integers
print(pigeonhole_sort(a))
print(a)