{"id":"frequency-map-pair-counting-avoids-quadratic","text":"Pair-counting solutions (e.g., absolute-difference-k) use `Counter` to reduce O(n^2) index enumeration to O(n) frequency multiplication — checking only `v + k` (not `v - k`) to prevent double-counting.","truth_value":"IN","source":"entries/2026/06/06/count-number-of-pairs-with-absolute-difference-k-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"frequency-map-pair-counting-avoids-quadratic","truth_value":"IN","reason":"premise"}]}}