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  1. Count Triplets
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Count Triplets

  • [deleted]     + 1 comment

    Hello!

    I'm learning Java, this solution was converted from @Jugad's Javascript solution, but I'm failing test cases 6 and 10. Can anyone help?

    // Complete the countTriplets function below.
    static long countTriplets(List<Long> arr, long r) {
        //0. Initializations
        Map<Long, Long> singleCounts = new HashMap<>();
        Map<Long, Long> pairCounts = new HashMap<>();
        long triplets = 0;
        
        //1. Sort array ascending order
        Collections.sort(arr, Collections.reverseOrder());
        
        //2. Iterate through sorted array
        for (Long num: arr) {
            // A. Count completed pairs
            if (pairCounts.get(num*r) != null) {
                triplets += pairCounts.get(num*r);
            }
            // B. Increment pair counts if needed
            if (singleCounts.get(num*r) != null) {
                pairCounts.merge(num, singleCounts.get(num*r), Long::sum);
            }
            // C. Increment single counts
            singleCounts.merge(num, Long.valueOf(1), Long::sum);
            
        }
        return triplets;
    }