{"id":"counter-two-pass-frequency-pipeline","text":"Frequency-based problems follow a standard two-pass pipeline: Counter construction in O(n) followed by a linear scan over the frequency map, with the scan phase specializing across three modes — uniqueness finding (first/kth element with count==1), extremal extraction (max frequency), and group counting (how many keys match a frequency predicate).","truth_value":"IN","source":"","source_url":"","source_hash":"","justifications":[{"type":"SL","antecedents":["counter-two-pass-uniqueness-pattern","counter-two-pass-max-then-count","counter-then-deduplicate-idiom"],"outlist":[],"label":"Three unused counter beliefs share the build-then-scan pipeline structure"}],"dependents":[],"metadata":{"source_type":"derived","last_reviewed":"2026-06-07T22:02:22","review_result":"unnecessary"},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"counter-two-pass-frequency-pipeline","truth_value":"IN","reason":"SL justification valid","antecedents":["counter-two-pass-uniqueness-pattern","counter-two-pass-max-then-count","counter-then-deduplicate-idiom"],"label":"Three unused counter beliefs share the build-then-scan pipeline structure"},{"node":"counter-two-pass-uniqueness-pattern","truth_value":"IN","reason":"premise"},{"node":"counter-two-pass-max-then-count","truth_value":"IN","reason":"premise"},{"node":"counter-then-deduplicate-idiom","truth_value":"IN","reason":"premise"}]}}