{"id":"per-problem-data-structure-isolation","text":"Each problem directory defines its own data structures (e.g., `TreeNode` in `sum-of-left-leaves`) rather than importing from a shared utility module, maintaining per-problem self-containment.","truth_value":"IN","source":"entries/2026/06/06/sum-of-left-leaves-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":["duplication-over-shared-infrastructure"],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"per-problem-data-structure-isolation","truth_value":"IN","reason":"premise"}]}}