Status: IN
Data structures and helpers are systematically duplicated per problem directory rather than factored into shared modules, trading DRY for zero coupling across 400+ solutions.
Architecture deliberately prioritizes isolation over deduplication
Depends on (SL): treenode-is-de-facto-shared-via-inline-copies, tree-serialization-helpers-duplicated, per-problem-data-structure-isolation, repo-no-cross-problem-imports