Archives

A retrospective on a few hobby projects that I worked on earlier this year.

We wrote four hash map implementations, predicted how they'd perform, and declared open addressing the winner. Then we changed the key distribution and watched the winner become 11,000x slower.

I accidentally implemented SPFA while thinking I was doing BFS with relaxation, then had to build a min-heap from scratch before I could do Dijkstra properly.

My first "arena" trie wasn't an arena at all — fixing that revealed real cache locality effects, disassembly surprises, and data-oriented design wins.

Implementing a trie led me into cache effects, const_cast, and what the compiler can and can't optimize away.

A completely opaque data structure turned out to be a flat array of ints with two elegant optimizations — I benchmarked each one to understand what it actually contributes.

How I built a ptrace-based sampling profiler for Linux/AArch64 — what I wrote, what Claude wrote, and where it helped and didn't.

How I completed all 50 stars of Advent of Code 2024 using C++20.

A short post about learning German — written in both German and English.