{"id":"canonical-form-frequency-counting-pattern","text":"Multiple solutions (domino pairs, good pairs, similar strings) reduce pair/group-counting problems to: canonicalize each element, count frequencies, then derive the answer from counts — avoiding O(n^2) pairwise comparison.","truth_value":"IN","source":"entries/2026/06/06/number-of-equivalent-domino-pairs-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"canonical-form-frequency-counting-pattern","truth_value":"IN","reason":"premise"}]}}