Austin Yang

A from-scratch rules engine for 斗地主 (Dou Dizhu) paired with a Monte Carlo tree search decision engine including UCT selection, expansion, rollout, and backpropagation — tuned across thousands of self-play games.

A rootless Linux container runtime in C using clone() with multiple namespaces, cgroups v2 for resource limits, pivot_root() for filesystem isolation, and libcap/seccomp for capability dropping and syscall filtering without root access.

A 64-bit dynamic memory allocator built from scratch in C using explicit doubly-linked free list, first-fit placement, boundary-tag coalescing, block splitting, and page-aligned heap extension via a custom mmap-backed sbrk model. Block metadata packed into 64-bit bitfield headers with matching footer tags.

A Linux debugger in C built on ptrace() with single-step execution, software breakpoints with INT3 injection, saved-byte restoration and RIP rollback, and byte-level memory access. Parses ELF section headers to resolve symtab/strtab and walk saved RIP chains into a full stack backtrace.

A build system clone with regex-based Makefile parsing, DAG dependency resolution with cycle detection, stat()-driven staleness checks, and a custom binary serialization library used to cache parsed rules across runs.