python 使用遞歸法對整數進行因數分解

from random import randint

def factors(num, fact = []):
    #每次從2開始查找因數
    for i in range(2, int(num**0.5) + 1):
        if num % i == 0:
            fact.append(i)
            factors(num // i, fact)
            break
    else:
        fact.append(num)

facts = []
n = randint(2, 10**8)
factors(n, facts)
result = '*'.join(map(str, facts))#把facts里的元素，全部轉化成字符
#並用*號連接起來，形成一個長的字符串 表達式
if n == eval(result):
    print(n, '= ' + result)