{"id":"two-sum-complement-lookup-pattern","text":"`twoSum` uses a hash map keyed by value (not index) to check whether the complement `target - num` has been seen, which is the canonical O(n) complement lookup idiom","truth_value":"IN","source":"entries/2026/06/06/two-sum-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":["two-sum-family-spans-lookup-strategy-space"],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"two-sum-complement-lookup-pattern","truth_value":"IN","reason":"premise"}]}}