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The Collatz conjecture

The Collatz conjecture#

The Collatz conjecture suggests that if you pick any positive integer, iterating the following process will always arrive at 0:

  1. If your number is even, halve it.

  2. If your number is odd, triple it and add one.

Define a python iterator Collatz(n) whose constructor takes a starting number and iterates the Collatz process until 1 is reached.

Here’s an example interaction:

>>> Collatz(5)
<__main__.Collatz object at 0x7faf747aad00>
>>> for x in Collatz(5): print x
    File "<stdin>", line 1
        for x in Collatz(5): print x
                                   ^
SyntaxError: invalid syntax
>>>
>>> for x in Collatz(5): print(x)
...
5
16
8
4
2
1
>>> Collatz(0)
Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/home/task.py", line 4, in __init__
        assert n >= 1, "n must be positive"
AssertionError: n must be positive
>>> Collatz(1.3)
Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/home/task.py", line 3, in __init__
        assert isinstance(n, int), "n must be an int"
AssertionError: n must be an int