Write, shorten, optimize

By Andrey Karpov | Jul 23, 2026 01:43 AM | Tags: static_cast refactoring optimization

I stumble upon a C++ function that will be a really illustrative example of how refactoring can both shorten and optimize code. Today, we'll need to dust off our human brains in the era of vibe coding and recall what it's like to know what the good is and what the bad is—after all, someone has to do it.

Write, shorten, optimize

by Andrey Karpov

From the article:

Let's see how these implementations compare in reality. Designing a fair benchmark took a bit of effort. First, I had to ensure the input data couldn't overflow a 64-bit signed integer, since signed overflow is undefined behavior and would invalidate the measurements. Second, to make the contest fair, the test cases alternated between arrays with and without zero elements. Finally, the input arrays had varying lengths.

I'm not claiming that the measurements are rigorous, but they represent a general idea. The speed of the first original algorithm is taken as the baseline. I used Clang with the -O2 and -m64 options. The original version with two loops: 1. My version with a single loop: 0.88. The Claude version with a single multiplication: 0.92.