Sum_of_four_values.cpp

// C++ program to find four  
// elements with the given sum 
#include <bits/stdc++.h>
using namespace std;
 
// Function to find 4 elements that add up to 
// given sum 
void fourSum(int X, int arr[], map<int, 
             pair<int, int>> Map, int N) 
{ 
    int temp[N]; 
 
    // Iterate from 0 to temp.length 
    for (int i = 0; i < N; i++) 
        temp[i] = 0; 
 
    // Iterate from 0 to arr.length 
    for (int i = 0; i < N - 1; i++) 
    { 
 
        // Iterate from i + 1 to arr.length 
        for (int j = i + 1; j < N; j++)
        { 
 
            // Store curr_sum = arr[i] + arr[j] 
            int curr_sum = arr[i] + arr[j]; 
 
            // Check if X - curr_sum if present 
            // in map 
            if (Map.find(X - curr_sum) != Map.end()) 
            { 
 
                // Store pair having map value 
                // X - curr_sum 
                pair<int, int> p = Map[X - curr_sum]; 
 
                if (p.first != i && p.second != i 
                    && p.first != j && p.second != j 
                    && temp[p.first] == 0
                    && temp[p.second] == 0 && temp[i] == 0
                    && temp[j] == 0)
                { 
 
                    // Print the output 
                    cout << arr[i] << "," << arr[j] <<
                      "," << arr[p.first] << "," << arr[p.second];
                    temp[p.second] = 1; 
                    temp[i] = 1; 
                    temp[j] = 1; 
                    break; 
                } 
            } 
        } 
    } 
} 
 
// Program for two Sum 
map<int, pair<int, int>> twoSum(int nums[], int N) 
{ 
    map<int, pair<int, int>> Map; 
    for (int i = 0; i < N - 1; i++)
    { 
        for (int j = i + 1; j < N; j++)
        { 
            Map[nums[i] + nums[j]].first = i;
            Map[nums[i] + nums[j]].second = j;
        } 
    } 
    return Map; 
} 
 
// Driver code
int main()
{
    int arr[] = { 10, 20, 30, 40, 1, 2 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 
    int X = 91; 
    map<int, pair<int, int>> Map = twoSum(arr, n); 
     
    // Function call 
    fourSum(X, arr, Map, n); 
 
    return 0;
}