{"id":"counter-filter-idiom","text":"Frequency-based problems use `collections.Counter` plus a generator expression to filter and aggregate, avoiding intermediate list allocation — a recurring pattern across the repo.","truth_value":"IN","source":"entries/2026/06/06/sum-of-unique-elements-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"counter-filter-idiom","truth_value":"IN","reason":"premise"}]}}