给一个正整数，如果是偶数，则减半；如果是奇数，则变为它的三倍加一。直到变为一停止。
对于所有正整数经过足够多次变换最终总能达到1。
#!/usr/bin/env python
# -*- coding: utf-8 -*-
def collatz(number):
while(number != 1):
if number % 2 == 0:
number = number // 2
print(number)
else:
number = 3 * number + 1
print(number)
if __name__ == '__main__':
try:
# 输入一个大于0的整数
number = abs(int(input("Enter a number:")))
if number != 0:
collatz(number)
else:
print("Pointless!")
except:
print("Input error!")用列表：
#!/usr/bin/env python
# -*- coding: utf-8 -*-
def collatz(number):
numbers = []
while(number != 1):
if number % 2 == 0:
number //= 2
else:
number = 3 * number + 1
numbers.append(number)
return numbers
if __name__ == '__main__':
number = raw_input("Enter a number:")
if number.isdigit() and int(number) != 0:
number = int(number)
numbers = collatz(number)
print(numbers)
else:
print("Input error!")
