Detect narcissistic numbers.

narcissist.py

from collections import defaultdict
from time import time

def is_narcissistic(x):
    sum = 0
    digits = sorted([int(digit) for digit in str(x)], reverse=True)
    power = len(digits)
    for digit in digits:
        sum += powers[power][digit]
        if sum > x:
            return False
    return sum == x

def precompute_powers(n):
    powers = defaultdict(dict)
    for i in range(2, n+1):
        for digit in range(10):
            powers[i][digit] = digit ** i
    return dict(powers)

upper_bound = 100000000000
powers = precompute_powers(len(str(upper_bound)))

start = time()
for number in range(11, upper_bound):
    if is_narcissistic_memory(number):
        print("[{:8.3f}] {}".format(time()-start, number))

that reverse sort is nice! works well with the escape door of if sum > x