Question

How to print all distinct 4 elements from an array that have the same given sum in C++

Answer 1

#include <iostream>
#include <algorithm>

void getDistinct4Elements(int arr[], int size, int sum) {
    std::sort(arr, arr + size);
 
    for (int i = 0; i <= size - 4; i++) {
        for (int j = i + 1; j <= size - 3; j++) {
            int k = sum - (arr[i] + arr[j]);
 
            int fromstart = j + 1, fromend = size - 1;
 
            while (fromstart < fromend) {
                if (arr[fromstart] + arr[fromend] < k) {
                    fromstart++;
                }
 
                else if (arr[fromstart] + arr[fromend] > k) {
                    fromend--;
                }
 
                else {
                    std::cout << arr[i] << ", " << arr[j] << ", ";
                    std::cout << arr[fromstart] << ", " << arr[fromend] << "\n";
                    fromstart++;
                    fromend--;
                }
            }
        }
    }
}
 
int main()
{
    int arr[] = { 4, 8, 1, 5, 9, 0, 3, 7 };
    
    int sum = 18;
 
    int size = sizeof(arr) / sizeof(arr[0]);
 
    getDistinct4Elements(arr, size, sum);
}

  
  
  
  
/*
run:
  
0, 1, 8, 9
0, 3, 7, 8
0, 4, 5, 9
1, 3, 5, 9
1, 4, 5, 8
  
*/

 

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