{"id":"merge-similar-items-uses-defaultdict-accumulation","text":"`sum_weights` uses `defaultdict(int)` to merge both lists in O(n) time before a single O(n log n) sort, rather than a two-pointer merge on pre-sorted input.","truth_value":"IN","source":"entries/2026/06/06/merge-similar-items-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"merge-similar-items-uses-defaultdict-accumulation","truth_value":"IN","reason":"premise"}]}}