base10 game

from itertools import permutations

def find_sum_equal_n():
    n = 0
    num = range(10)
    solutions = set()
    for perm in permutations(num):
        tple = product_sum(perm)
        if product_num(tple) == n:
            tple = well_ordered(tple)
            solutions.add(tple)
    return list(solutions)

def product_num(tple):
    total = tple[0]*tple[1] - tple[2]*tple[3]
    return total

def product_sum(perm):
    num1 = 100*perm[0] + 10*perm[1] + perm[2]
    num2 = 10*perm[3] + perm[4]
    num3 = 100*perm[5] + 10*perm[6] + perm[7]
    num4 = 10*perm[8] + perm[9]
    return (num1, num2, num3, num4)

def well_ordered(tple):
    a = max(tple[0], tple[1])
    b = min(tple[0], tple[1])

    c = max(tple[2], tple[3])
    d = min(tple[2], tple[3])

    if a > c:
        tple = (a,b,c,d)
    else:
        tple = (c,d,a,b)
    return tple


def display_solutions(lst):
    print '============================================'
    for solution in lst:
        display_sum(solution)
        print '============================================'


def display_sum(tple):
    print '   ' + str_num(tple[0], 3) + ' x ' + str_num(tple[1], 2)
    print ' - ' + str_num(tple[2], 3) + ' x ' + str_num(tple[3], 2)
    print ' = ', product_num(tple)


def str_num(num, length):
    str_num = str(num)
    diff = max(length - len(str_num), 0)
    string = ' '*diff
    string += str_num
    return string

if __name__ == '__main__':

    lst = find_sum_equal_n()
    display_solutions(lst)
    print len(lst)