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factor.py
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factor.py
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#!/usr/bin/env python
#-*- encoding: UTF-8-*-
"""
@desc
质因数分解python语言示例
一个偶数可以 分解为若干个质数相乘。
"""
import time
def factorize1(num):
i = 2
result = []
while (num > 1):
while (num % i == 0):
result.append(i)
num = num / i
i = i + 1
print(result)
"""
def factorize(num):
i = 2
result = []
while (num >= i * i):
while (num % i == 0):
result.append(i)
num = num / i
i = i + 1
if (num > 1):
result.append(num)
return result
"""
def factorize(num):
i = 2
result = []
while (num >= i * i):
if (num % i == 0):
print('num:', num)
result.append(i)
num = num / i
else:
i = i + 1
if (num > 1):
result.append(num)
return result
if __name__ == '__main__':
# 1. factorize1
num = 20
print(num)
start_time = time.time()
arr = factorize1(num)
print("time:" + str((time.time() - start_time) * 1000) + " ms")
# 2. factorize2
num = 20
print("%d =") %(num),
start_time = time.time()
arr = factorize(num)
size = len(arr)
for i in range(size):
print(arr[i]),
if (i < size - 1):
print("*"),
print("\n")
flag = " * "
print("%d = %s" % (num, flag.join([str(item) for item in arr])))
print(str(num) + " = " + flag.join(map(str, arr)))
print("\r\ntime:" + str((time.time() - start_time) * 1000) + " ms")
"""
jarry@jarrys-MacBook-Pro factor % python --version
Python 2.7.16
jarry@jarrys-MacBook-Pro factor % python factor.py
20
[2, 2, 5]
time:0.014066696167 ms
20 = 2 * 2 * 5
time:0.00905990600586 ms
*/
"""