第十九题

题目

一个数如果恰好等于它的因子之和，这个数就称为"完数"。例如6=1＋2＋3.编程找出1000以内的所有完数。

my_code:

import numpy as np
def factor(num):
    a = []
    for i in range(2,num):
        if num % i ==0:
            a.append(i)
    a.append(1)
    a = list(set(a))
    if np.sum(a)== num:
        return True
    else:
        return False

for i in range(2,1001):
    if factor(i):
        print('%i is a perfect number'%i)

输出：
> 6 is a perfect number
> 28 is a perfect number
> 496 is a perfect number

Reference code:

from sys import stdout
for j in range(2,1001):
    k = []
    n = -1
    s = j
    for i in range(1,j):
            if j % i == 0:
                n += 1
                s -= i
                k.append(i)
    
    if s == 0:
        print j
        for i in range(n):
            stdout.write(str(k[i]))
            stdout.write(' ')
        print k[n]

** 注意 **：sys.stdout.write()函数类似于print函数，两者之间的区别详见链接