narcissist.py

__author__ = "Sean Fitzgerald <sean@fitzgeralds.me>"

import math
import time


def is_narcissistic(x):
    result = 0
    x_str = list(str(x))
    x_str.sort(reverse=True)
    return compute_narc(x_str, x)


def compute_narc(digits, cache=[]):
    return sum([cache[digit] for digit in digits])

def int_to_sorted_digits(i):
    l = list(str(i))
    l.sort(reverse=True)
    return [int(x) for x in l]



def generate_digit_sorted_numbers(length):
    numbers = [9] * length
    while numbers[0] > 0:
        idx = -1
        if numbers[idx] >= 0:
            yield numbers
            numbers[idx] -= 1
        else:
            first_0 = numbers.index(-1)
            numbers[first_0 - 1] -= 1
            cur = first_0
            while cur < length:
                numbers[cur] = numbers[cur - 1]
                cur += 1

def compare_lists(list1, list2):
    if len(list1) != len(list2):
        return False
    for i in xrange(len(list1)):
        if list1[i] != list2[i]:
            return False

    return True




if __name__ == "__main__":
    import sys
    start_ts = time.time()
    min_length=2
    if len(sys.argv) > 1:
        min_length = int(sys.argv[1])

    for i in xrange(min_length, 61):
        results = set()
        pow_cache=[j**i for j in range(0, 11)]
        for row in generate_digit_sorted_numbers(i):
            narc = compute_narc(row, pow_cache)
            narc_digits = int_to_sorted_digits(narc)
            if compare_lists(row, narc_digits):
                results.add(narc)
        for narc in sorted(results):
            print("[{:8.3f}] {}".format(time.time() - start_ts, narc))