Maximum count of equal numbers in an array after performing given operations in C++

C++Server Side ProgrammingProgramming

We are given with an array of integers. The goal is to find the maximum numbers in array that are equal after performing given operations −

  • Select two elements a[i] and a[j] such that i != j and

  • Increment a[i] and decrement a[j] ( a[i]++,a[j]-- )

We will take the sum of the array and divide it by the number of elements. If N is size of array then

If sum is divisible by N then equal numbers will also be N otherwise Equal numbers will be N-1.


Arr[]= { 1,2,3 }


Maximum count of equal numbers : 3

Explanation − After first step Arr[] = { 2,2,2 } increment 1 and decrement 3 Sum of elements is 1+2+3=6, 6%3==0, therefore equal numbers=3


Arr[]= { 1,2,4 }


Maximum count of equal numbers : 2

Explanation − After first step Arr[] = { 1,3,3 } increment 2 and decrement 4 Sum of elements is 1+2+4=7, 7%3==1, therefore equal numbers=3-1=2

Approach used in the below program is as follows

  • The integer array Arr[] is used to store the integers.

  • Integer ‘size’ stores the length of the array.

  • Function maxEqual( int arr[], int n) takes an array , its size as input and returns the maximum count of equal numbers present in the array after applying a given operation.

  • First of all we will calculate the sum of array elements and store in ‘sum’

  • Now check divisibility of sum by size n (sum%n==0).

  • If divisible then return n

  • Else return n-1 as result.


 Live Demo

#include <bits/stdc++.h>
using namespace std;
int maxEqual(int arr[], int n){
   int sum = 0;
   for (int i = 0; i < n; i++){
      sum += arr[i];
   if (sum%n==0){
      return n;
   return n-1;
int main(){
   int Arr[] = { 1, 4, 1, 2};
   // size of an array
   int size =4;
   cout <<" Maximum count of equal numbers :"<< maxEqual(Arr,size);
   return 0;


Maximum count of equal numbers: 4
Published on 28-Jul-2020 14:32:19