I think you might be approaching this from a wrong angle. To solve this challenge, you do not have to know how BigInt works internally. To solve this challenge, you need to figure out how to do multiplication of large numbers. And there is many ways to do this, and one of such ways is taught in schools.

Forget BigInt, forget inheritances, forget how javascript objects work under the hood. There is no need for it here. You know how to multiply two large numbers without a computer, right? You can use the same approach to solve this task.

I really like this kata, thank you! One note - I wish the prompt had any context whatsoever other than don't use BigInt. I'm trying to strengthen my understansing of algos, and I'm down a rabbit hole researching how javascript objects work under the hood and working my way up in inheritence. If this was a little more focused, without giving away too much, it could be super helpful for my learning. I may be going too deep and little doses of understanding and building on that would be better pedogocially speaking. Maybe a way to frame the prompt in a way to build off some intermediate knowledge as a starting point to discover something more advanced about how BigInt works.

Java translation!!

p.s. thanks for checking :)

For javascript I have the next error:

ReferenceError: Test is not defined

The kata is nice, but maybe 6 kyu rate will be more appropriate for this one. And also I think that adding the OOP tag would be useful

Thankyou hobovsky and trash_incel. The addition of << std::flush allowed me to see that to my surpise the program crashed on the very first test with inputs "2" and "3" even though this compiled and ran with correct result locally. From there I deduced I was getting a -1 index. I had been looping using reverse iterator and was trying to compute the index for my vector to store the computation results using std::distance. This is were things were wrong. I guess that I was either lucky locally or my compiler was doing something smart. I had already made one of my own tests with one number as "" and again this compiled fine and gave the correct result for me locally. Anyway - I have now submitted with success. Thanks both.

add << std::flush after the values you print. flushing the standard output ensures you will see it even if the program crashes

This part, and specifically the READ at 0x000000000000, usually means that the error is caused by reading a past-the-end iterator:

==1==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x000000000000 [...]
==1==The signal is caused by a READ memory access.

Note that in this kata it is possible to receive "" as an input (don;t ask me why), and it should be treated as "0".

On c++ when running test I get the following STDERR:
double free or corruption (out)
UndefinedBehaviorSanitizer:DEADLYSIGNAL
==1==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f0db73858e0 bp 0x7ffc65681330 sp 0x7ffc656810e0 T1)
==1==The signal is caused by a READ memory access.
==1==Hint: address points to the zero page.
==1==WARNING: invalid path to external symbolizer!
==1==WARNING: Failed to use and restart external symbolizer!
#0 0x7f0db73858df (/lib/x86_64-linux-gnu/libc.so.6+0x408df)
#1 0x7f0db73ce836 (/lib/x86_64-linux-gnu/libc.so.6+0x89836)
#2 0x7f0db73d58b9 (/lib/x86_64-linux-gnu/libc.so.6+0x908b9)
#3 0x7f0db73dce49 (/lib/x86_64-linux-gnu/libc.so.6+0x97e49)
#4 0x42574d (/workspace/test+0x42574d)
#5 0x428475 (/workspace/test+0x428475)
#6 0x426b2e (/workspace/test+0x426b2e)
#7 0x426673 (/workspace/test+0x426673)
#8 0x4262ab (/workspace/test+0x4262ab)
#9 0x42bb25 (/workspace/test+0x42bb25)
#10 0x42584d (/workspace/test+0x42584d)
#11 0x7f0db7366c86 (/lib/x86_64-linux-gnu/libc.so.6+0x21c86)
#12 0x4045a9 (/workspace/test+0x4045a9)

UndefinedBehaviorSanitizer can not provide additional info.
==1==ABORTING

When I compile my code locally with: $ g++ -ggdb -pedantic-errors -Wall -Weffc++ -Wextra -Wconversion -Wsign-conversion -std=c++17 multiply.cpp -o prog I get no errors. There is a warning about conversion to long unsigned int from int on my variable index which I use to hold a "std::vector<>" result. The program runs with the given tests. I tried using std::cout << "a: " << a << '\n'; and std::cout << "b: " << b << '\n'; to see what inputs the problem might be associated with but this did not work on test. Can someone please advise how I might find th bug?

Python, JavaScript, PHP:

Wrong array dimension in the describe block message, 'Simple 3x3 arrays' should be 'Simple 3x2 arrays'

Enabled in this fork

At least javascript:

• Tests should fail without errors if the result is not an array.
• Tests should accept pairs [a,b] where a > b (descritpion explicitly says that 256 -> [[8,2],...] is valid).

In Python, the submission tests go up to 1000 while the description only states that inputs go to 500.

Depending on the tests in the other languages, either the description should be updated or the Python tests should be changed to match the description.