Yes, it's a good approach, I think. I came up with basically the same solution.

One critique: You don't need to collect the Map iterator into a Vec inside the flat_map() closure. That Vec just gets immediately turned back into an iterator via its .into_iter() method, so you might as well cut out the middle man and return the Map instead.

spoiler flag, plz...

It is.

thanks, this really explains why the test fails but it's strange that this detail is not written anywhere.

Because the number of times the element appears in each array has to be the same. If you square the elements in a, you get [4, 4, 9], 4 appears in a twice, but only once in b; and 9 appears in a only once, but it appears in b twice.

There is no bug. I don't even understand what you are talking about (what points to True??).

Do not raise issue so lightly, please refer to the documentation: https://docs.codewars.com/training/troubleshooting/

Why does test 10 expect False if the inputs [2, 2, 3] [4, 9, 9] exactly point to True? Or am I dumb or is this a bug

"())((("        |"())((("
...^            |...^
"()(((("        |"()(((("
.....^          |....^
"()(()("        |"()()(("
......^         |......^
"()(())"        |"()()()"

"())()))))()()("
..^
"(()()))))()()("
...^
"(((()))))()()("
.........^
"(((())))(()()("
..............^
"(((())))(()())"

I am little confused about this sample test case: "())()))))()()("
Could someone please explain to me why the answer is 4?

well... you are right!

i forgot to try such a simple optimization as avoiding consecutive div_assign

You're right!

Nothing wrong with this, but you could just remove the return keyword and the ; symbol.

I think you weren't supposed to change the 'function signature'.

really good... NOT!!