Sean William CarrollSean Carroll's personal website.https://www.seanwilliamcarroll.com/Four Hash Maps, Three Key Distributions, and One Catastrophehttps://www.seanwilliamcarroll.com/posts/hash-map-baseline/https://www.seanwilliamcarroll.com/posts/hash-map-baseline/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.Tue, 24 Mar 2026 05:01:00 GMTWhen BFS Isn't Enough: From SPFA to Dijkstra on Network Delay Timehttps://www.seanwilliamcarroll.com/posts/network-delay-spfa-to-dijkstra/https://www.seanwilliamcarroll.com/posts/network-delay-spfa-to-dijkstra/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.Wed, 18 Mar 2026 05:01:00 GMTBenchmarking Tries, Part 2: What "Arena" Actually Meanshttps://www.seanwilliamcarroll.com/posts/benchmarking-tries-part-2/https://www.seanwilliamcarroll.com/posts/benchmarking-tries-part-2/My first "arena" trie wasn't an arena at all — fixing that revealed real cache locality effects, disassembly surprises, and data-oriented design wins.Mon, 16 Mar 2026 05:01:00 GMTBenchmarking Tries: Arena vs unique_ptrhttps://www.seanwilliamcarroll.com/posts/benchmarking-tries/https://www.seanwilliamcarroll.com/posts/benchmarking-tries/Implementing a trie led me into cache effects, const_cast, and what the compiler can and can't optimize away.Sun, 15 Mar 2026 05:01:00 GMTBenchmarking Union-Find's Two Optimizationshttps://www.seanwilliamcarroll.com/posts/benchmarking-union-find/https://www.seanwilliamcarroll.com/posts/benchmarking-union-find/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.Sat, 14 Mar 2026 05:01:00 GMTBuilding a Sampling Profiler with Claudehttps://www.seanwilliamcarroll.com/posts/building-bench/https://www.seanwilliamcarroll.com/posts/building-bench/How I built a ptrace-based sampling profiler for Linux/AArch64 — what I wrote, what Claude wrote, and where it helped and didn't.Wed, 11 Mar 2026 13:00:00 GMTAdvent of Code 2024https://www.seanwilliamcarroll.com/posts/aoc_2024/https://www.seanwilliamcarroll.com/posts/aoc_2024/How I completed all 50 stars of Advent of Code 2024 using C++20.Sat, 10 May 2025 18:10:11 GMTWer bin ich? (Who am I?)https://www.seanwilliamcarroll.com/posts/wer_bin_ich/https://www.seanwilliamcarroll.com/posts/wer_bin_ich/A short post about learning German — written in both German and English.Fri, 09 May 2025 14:47:27 GMT