We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  1. Count Triplets
  2. Discussions

Count Triplets

  • babakhonza
     + 1 comment

    Eritorial transformed into Java. Don't forget to check if number is divisible by r.

        // Complete the countTriplets function below.
    static long countTriplets(List<Long> arr, long r) {
        HashMap<Long, Long> right = new HashMap<>();
        HashMap<Long, Long> left = new HashMap<>();
        
        for (Long num : arr) {
            right.put(num, right.getOrDefault(num, 0L) + 1);
        }
        
        long tripletsCounter = 0;
        
        for (Long num : arr) {
            if (right.getOrDefault(num, 0L) > 0) {
                right.put(num, right.get(num) - 1);
            }
            if (num % r == 0) {
                tripletsCounter += right.getOrDefault(num * r, 0L) * left.getOrDefault(num / r, 0L);
            }
            left.put(num, left.getOrDefault(num, 0L) + 1);
        }
        
        return tripletsCounter;
    }