for me, this was the best, simple, though powerful algorithm of all time (for this code of course!), keep it up champ.

awesome

A regular expression can only match strings or bytes-like objects. Python, unlike JavaScript, does not convert numbers to strings automatically, something you can already see when doing "abc" + 1.

gauss gang rise up!

wow!

Did the exact same thing

按位与&
如果两个二进制位都为1，则结果为1，否则结果为0

Right, thank you for the reminder!

re.match() looks at the beginning of the string (see doc).
re.search() looks anywhere in the string (see doc).

The regex only checks, if the code contains a 1,2 or 3. It's not checking, if it starts with 1,2 or 3.

I wrote greet() { echo ... } and did not work (with '()'). Why does greet { echo ... } work?

can someone explain ?

love this solution