Problem 2.2 incomplete

n = "1211"
b = 10
k = len(n)
count = 1
def reps(n, b):
    def numtobase(n, b):
        num = []
        fin = []
        f = n
        while f != 0:
            num.append(f % b)
            f = f / b
        fin = num
        fin.reverse()
        return fin

    ascending = [int (i) for i in n]
    descending = [int (i) for i in n]

    ascending.sort()
    descending.sort()
    descending.reverse()

    x = 0
    y = 0

    for i in range(0, len(ascending)):
        y += ascending.pop() * (b**i)
        x += descending.pop()* (b**i)

    z = numtobase((x-y), b)
    while (len(z) < k):
        z.insert(0,0)
    basestr = ''.join(str(e) for e in z)
    return basestr
string = n
while(string != reps(string,b)):
    string = reps(string,b)
    count +=1

'''
flag = True
while flag:
    string = reps(string,b)
    if(string == n):
        flag = False
    count +=1
'''