TripletSum.java

// Triplet Sum
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// You have been given a random integer array/list(ARR) and a number X. Find and return the number of triplets in the array/list which sum to X.
// Note :
// Given array/list can contain duplicate elements.
// Input format :
// The first line contains an Integer 't' which denotes the number of test cases or queries to be run. Then the test cases follow.

// First line of each test case or query contains an integer 'N' representing the size of the first array/list.

// Second line contains 'N' single space separated integers representing the elements in the array/list.

// Third line contains an integer 'X'.
// Output format :
// For each test case, print the total number of triplets present in the array/list.

// Output for every test case will be printed in a separate line.
// Constraints :
// 1 <= t <= 50
// 0 <= N <= 10^2
// 0 <= X <= 10^9
// Time Limit: 1 sec
// Sample Input 1:
// 1
// 7
// 1 2 3 4 5 6 7 
// 12
// Sample Output 1:
// 5
// Sample Input 2:
// 2
// 7
// 1 2 3 4 5 6 7 
// 19
// 9
// 2 -5 8 -6 0 5 10 11 -3
// 10
// Sample Output 2:
// 0
// 5

//  Explanation for Input 2:
// Since there doesn't exist any triplet with sum equal to 19 for the first query, we print 0.

// For the second query, we have 5 triplets in total that sum up to 10. They are, (2, 8, 0), (2, 11, -3), (-5, 5, 10), (8, 5, -3) and (-6, 5, 11)

import java.util.Scanner;

public class TripletSum {

    public static void takeInput(int arr[], int n,Scanner s) {
        System.out.println("Enter Values Of The Array : ");
        for (int i = 0; i < n; i++) {
            arr[i] = s.nextInt();
        }
    }

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        System.out.print("Enter Number Of Test Cases : ");
        int t = s.nextInt();
        for (int i = 1; i <= t; i++) {
            System.out.print("Enter Length of " + i + " Array : ");
            int n = s.nextInt();
            int arr[] = new int[n];
            takeInput(arr, n,s);
            System.out.println("Enter Value Of The X : ");
            int x = s.nextInt();
            int ans = findTriplet(arr, n, x);
            System.out.println(ans);
            s.close();
        }
    }

    public static int findTriplet(int arr[], int n, int x) {
        int pairs = 0;
        for (int i = 0; i < n; i++) {
            for (int j = i+1; j < n; j++) {
                for (int k = j+1; k < n; k++) {
                    if (arr[i] + arr[j] + arr[k] == x) {
                        pairs++;
                    }
                }
            }
        }
        return pairs;
    }
}