Oh, you right about redundancy, i dont get it. I've seen your solution, can you explain how it works? I mean cnt variable and defining keys as a function

The boolean multiplication (c in b)* is redundant here, as - I have already commented this on another solution:

b.find(c) will return -1 if c is not in b, thus 1 + b.find(c) equals 0, not adding to the total sum.

I wouldn't say it is beautiful nor excellent.

beautiful use of boolean type, excelent solution

This solution works only for python 2. In python 2 when int number divides another int we get int rounded down number. In python 3 we would see float type number.
For example:
3/2=1 - round down and integer type (python 2)
3/2=1.5 - float (python 3)
Also, for making a float number in python 2 you need add a dot at the end of the code (ex. 3/2.=1.5)

Shouldn't it be [7,3]?

i've got only one error in 'ten millions numbers in middle pair' test . what can be wrong?

I don't understand what does this mean? at least, is this feedback wrong?

I solved this kata and submitted final solution, but after this i see "Solutions have been withheld". What's wrong?

How does it work?