[Tutor] Detect duplicate digits in a number

[Alan Gauld]

On 09/02/2022 01:39, Manprit Singh wrote:

> def detect_repeat(num):
>     lx = []
>     while num:
>         num, rem = divmod(num, 10)
>         if rem  in lx:
>             return False
>         lx.append(rem)
>     return True

I'd either rename the function to something like unique_digits()
or reverse the return values. If I saw code like

if detect_repeat(n):
    # do_something()

I'd expect do_something to be called if there were repeat
digits. You function reverses the logic implied by the name.

> len(set(str(2343))) == len(str(2343))
> that also produces the  desired result -False
> 
> The second solution according to me lacks readability and again there are
> lots of conversion str, set and all .

You can reduce the number of conversions by just doing it once:

s = str(n)
len(s) == len(set(s))

If you are concerned about performance test it. Try your function
versus the str/set test(in another function) and see which is fastest.
Your functuon is doing a lot of work so I wouldn't be surprised if
it's actually slower than the str/set approach.

> Just need your opinion and guidance . In the first solution If you can see,
> there are two return statements . Is this practice considered ok ?

Computer Science purists will say no.
Pragmatic programmers will say yes, it's very common.

-- 
Alan G
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