6 kyu
Multiply list by integer (with restrictions)
437 of 845suic
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On further experimentation, there are definitely JS test cases which expect the output to be
-0when both the multipland and multiplier are positive numbers.In one random test case, for example,
n(the multiplicand) is291and the first integer in the array (the multiplier) is0. The test is failing because it says that the result of that first multiplication is expected to be-0.If we could expect all such cases (where the multiplicand and multiplier are both positive) to result in a negative zero for some reason, then fine: we could work around it sensibly. But not all the test cases expect negative zero in this "positive times positive" scenario.
Right now, this kata as described seems unsolvable in JavaScript. Perhaps the description needs updated if there is some implicit requirement for returning negative zero in certain conventionally-unexpected cases. But more likely, there is a bug in the test solution.
Fixed.
Why are we still getting -0 in the "expected" results in this kata, particularly in JavaScript?
It's not even conventionally possible to check for -0 in JavaScript using operators, Math.sign(), or the rest of the Math library, as far as I can tell. You can't even use right-shift to find that.
(I can find two ways to do it, but they are both highly obscure and one of them appears to be undocumented. I will mention them in a comment below with a spoiler tag for those interested.)
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Fixed
Honestly it feels like the point of this is to not use multiplication and iteration over what you are given, but that is just my interpritation. This is a great Kata if you work under that idea but it seems most others went about it as finding built ins or other functions to get around the restrictions rather than figruing out the math solution.
C++ Translation.
I feel like banning the star operator makes sense in the Python translation but not JS. In Python, you can still multiply in a functional way without using the asterisk. In JS, not so much; there is nothing functional about the approach you'd have to take there.
Expected: '[-0, -357, 714, -1071, 1428, 1785, -2142, -2499, -2856, 3213, -3570, -3927, 4284, 4641, 4998, -5355, 5712, 6069, 6426, -6783, 7140, 7497, 7854, 8211, -8568, -8925, 9282, -9639, -9996, -10353, 10710, 11067, 11424, 11781, -12138, 12495, -12852, -13209, 13566, 13923, 14280, -14637, 14994, -15351]', instead got: '[0, -357, 714, -1071, 1428, 1785, -2142, -2499, -2856, 3213, -3570, -3927, 4284, 4641, 4998, -5355, 5712, 6069, 6426, -6783, 7140, 7497, 7854, 8211, -8568, -8925, 9282, -9639, -9996, -10353, 10710, 11067, 11424, 11781, -12138, 12495, -12852, -13209, 13566, 13923, 14280, -14637, 14994, -15351]'
It seems there is still a problem with negative zero.
python new test framework is required. updated in this fork
approved
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Expected: '[-0, -618, -1236, 1854, -2472, 3090, 3708, -4326, 4944, -5562, 6180, 6798, -7416, -8034, 8652, 9270, -9888, 10506, 11124, 11742, -12360, 12978, 13596]', instead got: '[0, -618, -1236, 1854, -2472, 3090, 3708, -4326, 4944, -5562, 6180, 6798, -7416, -8034, 8652, 9270, -9888, 10506, 11124, 11742, -12360, 12978, 13596]'
Realy '-0' for multiplication result is correct? What did I missed?
I have the same issue! :)
Hi, thanks for reporting. Try now. Regards, suic
I have the same problem
having the same issue on javascript
Had the same issue. Now I learned that something like a negative 0 exists
Had to solve it with a little workaround
Fixed
Hello! Can you answer me, how happened this? -938 * 0 === 0 And -874 * 0 === -1 What the difference?
Which language?
js
In JavaScript version,It seems that only positive integers are tested. How about negative integers? Some solutions might not be accepted. Like this: multiply(-1,[1,2,3]) Some solutions use "while",and might lead to "dead cycle".
Thanks, you are right. The description states "integer(s)" not "positive integers(s)". In fact the original Python version tests only positive numbers too. I've change both. Please check the JS version. Regards, suic
The l (list) array appears to be surrounded by quotation marks, is this the reason that when I try to convert it to a string I end up with blackslashes with my results?
Hi, sorry I don't understand your question. Can you paste here your code and mark it as a spoiler? Thanks, suic
javascript translation created.
Lovely kata, thank you, suic!
My first solved python-kata! :-)
WOW:-)... And just approved (average was 6kyu;-))
Good job! :)
WOW! suic is back!
Right, I'm back for a moment :) Things didn't change much during my break. I'll take another break as I have a pile of ("thick and heavy") books which I want/have to read :) Enjoy playing codewars :)
Regards,
suic
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Hi, interesting approach but you mustn't modify the input list. I've added it to description.
Thanks,
suic