Count the triplets - Given an array of distinct integers. The task is to count all the triplets such that sum of two elements equals the third element.

CountTriplets.java

import java.util.ArrayList;
import java.util.Collections;

public class CountTriplets {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ArrayList<Integer> inputList = new ArrayList<Integer>();
		for (int i = 0; i < args.length; i++) {
			inputList.add(Integer.parseInt(args[i]));
		}
		Collections.sort(inputList);
		int numOfTriplets=0;
		for (int i = 2; i < inputList.size(); i++) {
			int currentSum = inputList.get(i);
			for(int j=i-1;j>0;j--) {
				int currentNum = inputList.get(j);
				if(inputList.subList(0, j).contains(currentSum-currentNum)) {
					numOfTriplets++;
				}
			}
			
		}
		System.out.println("Total Number of Triplets " + numOfTriplets);
	}

}