Number of pairs with maximum sum in C++

Given an array, we need to find the number of pairs with maximum sum. Let's see an example.

Input

arr = [3, 6, 5, 2, 1, 2, 3, 4, 1, 5]

Output

2

The maximum pair sum is 10. There are 2 pairs with maximum sum. They are (5, 5) and (6, 4).

Algorithm

• Initialise the array with random numbers.
• Initialise the maximum sum to minimum.
• Iterate over the array with two loops.
• 
  
  • Find the maximum sum of pairs.
• Initialise the count to 0.
• Now, iterate over the array again.
• 
  
  • Increment the count if the current pair sum is equal to the maximum pair sum.
• Return the pairs count.

Implementation

Following is the implementation of the above algorithm in C++

#include <bits/stdc++.h>
using namespace std;
int getMaxSumPairsCount(int a[], int n) {
   int maxSum = INT_MIN;
   for (int i = 0; i < n; i++) {
      for (int j = i + 1; j < n; j++) {
         maxSum = max(maxSum, a[i] + a[j]);
      }
   }
   int count = 0;
   for (int i = 0; i < n; i++) {
      for (int j = i + 1; j < n; j++) {
         if (a[i] + a[j] == maxSum) {
            count++;
         }  
      }
   }
   return count;
}
int main() {
   int arr[] = { 3, 4, 5, 2, 1, 2, 3, 4, 1, 5 };
   int n = 10;
   cout << getMaxSumPairsCount(arr, n) << endl;
   return 0;
}

Output

If you run the above code, then you will get the following result.

1