tripletSum.cpp

// 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.
#include <iostream>
using namespace std;

int tripletSum(int *input, int size, int x)
{
    int count = 0;
 for (int i = 0; i < size - 2; i++)
    {
 
        // Fix the second element as A[j]
        for (int j = i + 1; j < size - 1; j++)
        {
 
            // Now look for the third number
            for (int k = j + 1; k < size; k++)
            {
                if (input[i] + input[j] + input[k] == x)
                {
                    count++;
                }
            }
        }
    }
    return count;
}

int main()
{
	int t;
	cin >> t;

	while (t--)
	{
		int size;
		int x;
		cin >> size;

		int *input = new int[size];

		for (int i = 0; i < size; i++)
		{
			cin >> input[i];
		}
		cin >> x;

		cout << tripletSum(input, size, x) << endl;

		delete[] input;
	}

	return 0;
}