koan | koan - kickstart over a network

You have probably misunderstood the question...

Return the set of products that were ordered by all customers

means

Give me the products that are been purchased by all customer

therefore, you don't want to return "all the products that are been purchased at least 1 time by any customer", but only those that every customer have bought at least one time

At the end, "mathematically speaking" you don't want an "union", but an "intersection"... and the collector has infact an intersect method...

OT note:
also, consider that your plus method is not doing anything to the set, and your code is equivalent to:

Do you have the Chinese ​(Simplified)​ Language Pack enabled in your PyCharm Professional 2021.1.1? If so, please try disabling it and opening the course once again.

There's a compatibility issue between mentioned language pack and Python courses in the EduTools plugin, and the developers are currently investigating it.

I would advise adding this issue to your watch list to be 100% sure that you won't miss any updates.

You could change the storage of the values a bit by taking an object with roman signs as keys and decimal values.

For crating a recursive function, you could add an exit condition which is here just a check for an empty string and return zero in this case.

Then check if two character are in the object and if so take the value and add the result of calling the function again with the rest of the string.

If not take only the first character and the value and call the function again for getting the rest of the string.

There's a parameter for it in the new plot_trace function. This does the trick;

Indeed, in the context of expressions (calculations), PowerShell indeed automatically widens anything that exceeds the max. value of [int] / [uint] (32-bit signed / unsigned integers) or [long] / [ulong] (64-bit) to [double], which is easy to verify^[1]:

I find the easiest thing to do is to use the NODE_OPTIONS environment variable instead:

So the range you define (0..9) is actually already a sequence of numbers. Instead of iterating and repeatedly generating a new random, you can just use a subset of that sequence. In fact, this is the accepted answer's solution to the question you linked. Here are some pointers if you want to implement it yourself to get the practice:

• The first for loop in that solution is unnecessary in Kotlin because of the range. 0..9 does the same thing, you're on the right track there.

• In Kotlin you can call .shuffled() directly on the range without needing to call Collections.shuffle() with an argument like they do.

• You can avoid another loop if you create a string from the whole range and then return a substring.

If you want to look at my solution (with input from others in the comments), it is in a spoiler here:

fun getUniqueNumber(length: Int) = (0..9).shuffled().take(length).joinToString('')

(Note that this doesn't gracefully handle a length above 10, but that's up to you to figure out how to implement. It is up to you to use subList() and then toString(), or toString() and then substring(), the output should be the same.)