Make all array elements equal by repeatedly replacing largest array element with the second smallest element

Given an array arr[] of size N, the task is to count the number of operations required to make all array elements equal by replacing the largest array element with the second-largest array element, which is strictly smaller than the largest array element.

Examples:

Input: arr[ ] = {1, 1, 2, 2, 3}
Output: 4
Explanation: A total of 4 operations are required to make all array elements equal.
Operation 1: Replace the largest element (= arr[4] = 3) with the next largest( = arr[2] = 2). The array arr[] modifies to {1, 1, 2, 2, 2}.
Operation 2: Replace the largest element (= arr[2] = 2) with the next largest( = arr[0] = 1). The array arr[] modifies to {1, 1, 1, 2, 2}
Operation 3:  Replace the largest element (= arr[3] = 2) with the next largest( = arr[0] = 1). The array arr[] modifies to {1, 1, 1, 1, 2}
Operation 4:  Replace the largest element (= arr[4] = 2) with the next largest( = arr[0] = 1). The array arr[] modifies to {1, 1, 1, 1, 1}

Input: arr[ ] = {1, 1, 1}
Output: 0

Approach: Follow the steps below to solve the problem:

• Initialize a variable, say value_count = 0 and operation_count = 0.
• Sort the array arr[] in ascending order.
• Traverse the array arr[] and check if the current element is greater than the previous element. If found to be true, then increase value_count by 1.
• For each iteration, add value_count in operation_count.
• Finally, print the value of operation_count.

Below is the implementation of the above approach:

// C++ program to Make all array elements
// equal by perform certain operation
#include <bits/stdc++.h>
using namespace std;

// Function to count number of operations
// required to make all array elements equal
int operation(int arr[], int n)
{
    // Initialize the val_count
    // and operation_count by 0.
    int val_count = 0, operation_count = 0;

    // Sort the array in ascending order.
    sort(arr, arr + n);

    for (int i = 1; i < n; i++) {

        // Current element greater
        // than the previous element
        if (arr[i - 1] < arr[i]) {

            // If yes then update the
            // val_count by 1.
            val_count++;
        }

        // Add the value_count in operation_count.
        operation_count = operation_count + val_count;
    }
    // Return the operation_count
    return operation_count;
}

// Driver Code
int main()
{
    // Given Input
    int arr[] = { 1, 1, 2, 2, 3 };
    int n = sizeof(arr) / sizeof(arr[0]);

    // Function Call
    cout << operation(arr, n);
    return 0;
}

// Java program for the above approach
import java.util.Arrays;
import java.io.*;

class GFG 
{

  // Function to count number of operations
  // required to make all array elements equal
  static int operation(int arr[], int n)
  {

    // Initialize the val_count
    // and operation_count by 0.
    int val_count = 0, operation_count = 0;

    // Sort the array in ascending order.
    Arrays.sort(arr);

    for (int i = 1; i < n; i++) {

      // Current element greater
      // than the previous element
      if (arr[i - 1] < arr[i]) {

        // If yes then update the
        // val_count by 1.
        val_count++;
      }

      // Add the value_count in operation_count.
      operation_count = operation_count + val_count;
    }
    // Return the operation_count
    return operation_count;
  }

  // Driver Code
  public static void main (String[] args)
  {

    // Given Input
    int arr[] = { 1, 1, 2, 2, 3 };
    int n = arr.length;

    // Function Call 
    System.out.println( operation(arr, n));
  }
}

// This code is contributed by Potta Lokesh

# Python3 program to Make all array elements
# equal by perform certain operation

# Function to count number of operations
# required to make all array elements equal
def operation(arr, n):
  
     # Initialize the val_count
    # and operation_count by 0.
    val_count = 0
    operation_count = 0
    
    # Sort the array in ascending order.
    arr.sort()
    for i in range(1, n):
      
         # Current element greater
        # than the previous element
        if arr[i-1] < arr[i]:
          
             # If yes then update the
            # val_count by 1.
            val_count += 1
            
        # Add the value_count in operation_count.   
        operation_count += val_count
        
    # Return the operation_count
    return operation_count

# Driver code
arr = [1, 1, 2, 2, 3]
n = len(arr)
print(operation(arr, n))

# This code is contributed by Parth Manchanda

// C# program for the above approach
using System;

public class GFG 
{

  // Function to count number of operations
  // required to make all array elements equal
  static int operation(int []arr, int n)
  {

    // Initialize the val_count
    // and operation_count by 0.
    int val_count = 0, operation_count = 0;

    // Sort the array in ascending order.
    Array.Sort(arr);

    for (int i = 1; i < n; i++) {

      // Current element greater
      // than the previous element
      if (arr[i - 1] < arr[i]) {

        // If yes then update the
        // val_count by 1.
        val_count++;
      }

      // Add the value_count in operation_count.
      operation_count = operation_count + val_count;
    }
    
    // Return the operation_count
    return operation_count;
  }

  // Driver Code
  public static void Main(String[] args)
  {

    // Given Input
    int []arr = { 1, 1, 2, 2, 3 };
    int n = arr.Length;

    // Function Call 
    Console.WriteLine( operation(arr, n));
  }
}

// This code is contributed by Amit Katiyar

// Javascript program to Make all array elements
// equal by perform certain operation

// Function to count number of operations
// required to make all array elements equal
function operation(arr, n) {
  // Initialize the val_count
  // and operation_count by 0.
  let val_count = 0,
    operation_count = 0;

  // Sort the array in ascending order.
  arr.sort();

  for (let i = 1; i < n; i++) {
    // Current element greater
    // than the previous element
    if (arr[i - 1] < arr[i]) {
      // If yes then update the
      // val_count by 1.
      val_count++;
    }

    // Add the value_count in operation_count.
    operation_count = operation_count + val_count;
  }
  // Return the operation_count
  return operation_count;
}

// Driver Code

// Given Input
let arr = [1, 1, 2, 2, 3];
let n = arr.length;

// Function Call
document.write(operation(arr, n));

// This code is contributed by gfgking.

4

Time Complexity: O(NLogN)
Auxiliary Space: O(1)