3numbers.cpp

// C++ program to find a triplet 
#include <bits/stdc++.h> 
using namespace std; 

// returns true if there is triplet with sum equal 
// to 'sum' present in A[]. Also, prints the triplet 
bool find3Numbers(int A[], int arr_size, int sum) 
{ 
	int l, r; 

	/* Sort the elements */
	sort(A, A + arr_size); 

	/* Now fix the first element one by one and find the 
	other two elements */
	for (int i = 0; i < arr_size - 2; i++) { 

		// To find the other two elements, start two index 
		// variables from two corners of the array and move 
		// them toward each other 
		l = i + 1; // index of the first element in the 
		// remaining elements 

		r = arr_size - 1; // index of the last element 
		while (l < r) { 
			if (A[i] + A[l] + A[r] == sum) { 
				printf("Triplet is %d, %d, %d", A[i], 
					A[l], A[r]); 
				return true; 
			} 
			else if (A[i] + A[l] + A[r] < sum) 
				l++; 
			else // A[i] + A[l] + A[r] > sum 
				r--; 
		} 
	} 

	// If we reach here, then no triplet was found 
	return false; 
} 

/* Driver program to test above function */
int main() 
{ 
	int A[] = { 1, 4, 45, 6, 10, 8 }; 
	int sum = 22; 
	int arr_size = sizeof(A) / sizeof(A[0]); 

	find3Numbers(A, arr_size, sum); 

	return 0; 
}