I implemented the STOC 2025 Best Paper Award winner in C99. The algorithm achieves O(m log^(2/3) n) complexity, breaking the 65-year-old sorting barrier for sparse directed SSSP that Dijkstra established at O(m + n log n).

*Key implementation details:* - Cache-optimized CSR layout for maximum spatial locality - Zero-allocation design with pre-allocated workspaces - Recursive subproblem decomposition instead of global priority queues

*Benchmarks:* On graphs with 250k–1M nodes, this shows 20,000x+ speedups over standard Dijkstra implementations. The DMMSY core runs in ~800ns for 1M nodes.

*Paper:* https://arxiv.org/pdf/2504.17033 *GitHub:* https://github.com/danalec/DMMSY-SSSP

This is experimental—focused on correctness first. Would love feedback on edge cases, better decomposition strategies, or cache-oblivious optimizations I might have missed.