Two-Sum.cpp

// Write a program that, given an array A[] of n numbers and another number x, determines whether or not there exist two elements in A[] whose sum is exactly x. 

// Input: arr[] = {0, -1, 2, -3, 1}
//         sum = -2
// Output: -3, 1
//          Valid pair exixts.
         
// If we calculate the sum of the output,
// 1 + (-3) = -2

// Input: arr[] = {1, -2, 1, 0, 5}
//        sum = 0
// Output:
//         No valid pair exists.

//solution

/*
* This C++ program tells if there exists a pair in array whose sum results in x.
*/

#include <iostream>

using namespace std;

// Function to find and print pair
bool chkPair(int A[], int size, int x) {
	for (int i = 0; i < (size - 1); i++) {
		for (int j = (i + 1); j < size; j++) {
			if (A[i] + A[j] == x) {
				cout << "Pair with a given sum " << x << " is (" << A[i] << ", " << A[j] << ")"
				<< endl;

				return 1;
			}
		}
	}

	return 0;
}

int main(void) {
	int A[] = {0, -1, 2, -3, 1};
	int x = -2;
	int size = sizeof(A) / sizeof(A[0]);

	if (chkPair(A, size, x)) {
		cout << "Valid pair exists" << endl;
	}
	else {
		cout << "No valid pair exists for " << x << endl;
	}

	return 0;
}

// This code is contributed by sujay (sujaykummari)