it can be improved vis intilaize

          size =matrix.size() ; 

outside the loop

nice shot!

I disagree. If you use one counter clang can't vectorize your code automatically using SIMD.

nice job using only one counter instead of two.

brilliant

very nice best practice and clever problem that has the blazingly fast speed of O(N^2)

welcome to codewars

Assigning size_t to int isn't safe.

There's an issue with empty vectors, easy to fix by moving "-1" to the left in the condition.

This first if condition is not needed here. If arr1 is empty, arr1.size() returns 0 and the second if condition is never executed. If arr2 is empty, for each statement is not executed and outArray is returned as an empty collection anyway.

Why is an O(n*2) solution considered a "best practice"?

Can you explain what you did changing n to a constant char? How is this used as a condition in the second parameter in the for loop