#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Filename: perfect_number.py
import time
from math import sqrt, floor
'''
' 创建一个完全数查找程序
'
' 完全数指其真因子相加等于数字本身的数字。
' 例如,6 是一个完全数,因为 6 的因子(不包括 6 本身)是 1、2 和 3,
' 而 1 + 2 + 3 = 6。
' 更规则的完全数定义是因子(不包括该数字本身)之和等于该数字的数字。
' 在我的示例中,计算结果是 1 + 2 + 3 + 6 - 6 = 6。
'''
def is_perfect(num):
sum = 1
for i in range(2, num):
if (num % i) == 0:
sum += i
return sum == num
def is_perfect2(num):
factors = []
sum = 1
for i in range(2, int(floor(sqrt(num))) + 1):
if (num % i) == 0:
factors.append(i)
if (num / i != i):
factors.append(num / i)
for f in factors:
sum += f
return sum == num
def is_perfect3(num):
sum = 1
for i in range(2, int(floor(sqrt(num))) + 1):
if (num % i) == 0:
sum += i
if (num / i != i):
sum += num / i
return sum == num
# Test
PERFECT_NUMS = [6, 28, 496, 8128, 33550336]
# 1
def test_perfect(proc):
for num in PERFECT_NUMS:
assert(proc(num))
# 2
def test_non_perfect(proc):
for i in range(2, 10000):
if PERFECT_NUMS.count(i) > 0:
assert(proc(i))
else:
assert(not proc(i))
assert(proc(PERFECT_NUMS[4]))
'''
start = time.time()
test_perfect(is_perfect)
test_non_perfect(is_perfect)
print "is_perfect took %f secs" % (time.time() - start)
'''
start = time.time()
test_perfect(is_perfect2)
test_non_perfect(is_perfect2)
print "is_perfect2 took %f secs" % (time.time() - start)
start = time.time()
test_perfect(is_perfect3)
test_non_perfect(is_perfect3)
print "is_perfect3 took %f secs" % (time.time() - start)