获取总位数并应用pow()函数

num = int(input("Enter a number: "))
num_digits = len(str(num))
sum = 0
temp = num
while temp > 0:
   digit = temp % 10
   sum += pow(digit, num_digits)
   temp //= 10
if num == sum:
   print(num,"is an Armstrong number")
else:
   print(num,"is not an Armstrong number")

您的算法错误。行：

sum += digit * 3

...应该是...

sum += digit ** 3

这显然是您的意图。但是，这只适用于3位数。一般方法可以这样实现：

from math import log10

def isArmstrong(n):
    _len = int(log10(n)) + 1
    _n = n
    _sum = 0
    while (_n > 0):
        _sum += (_n % 10) ** _len
        _n //= 10
    return _sum == n

示例：

# all values from 1-9 are Armstrong numbers so start from 10
for i in range(10, 1_000_000):
    if isArmstrong(i):
        print(i)

输出：

153
370
371
407
1634
8208
9474
54748
92727
93084
548834