{"id":"last-seen-stores-latest-index","text":"`last_seen[num]` always holds the most recent index where `num` appeared — the unconditional overwrite after each check maintains this invariant, which is what makes it safe to discard older indices.","truth_value":"IN","source":"entries/2026/06/06/contains-duplicate-ii-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"last-seen-stores-latest-index","truth_value":"IN","reason":"premise"}]}}