Find K such that changing all elements of the Array greater than K to K will make array sum N

Given an array arr[] and an integer N, the task is to find a number K from the given array such that if all the elements in the arr greater than K are changed to K then the sum of all the elements in the resulting array will be N. Print -1 if it is not possible.

Examples:

Input: arr[] = {3, 1, 10, 8, 4}, N = 16
Output: 4
If all the elements greater than 4 are changed to 4 then the resulting array will be {3, 1, 4, 4, 4}
Hence the sum will be 16 which is the required value of N.

Input: arr[] = {3, 1, 10, 8, 4}, N = 11
Output: -1

Approach: The idea is to use sorting to solve the above problem.



  • First, sort the array in ascending order.
  • Then traverse the array and for each element arr[i].
  • Assume that all the elements after it has been changed to arr[i] and calculate the sum.
  • If it is equal to N then return arr[i].
  • If the end of the array is reached then print -1.

Below is the implementation of the above approach:

CPP

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ implementation of the approach
  
#include <bits/stdc++.h>
using namespace std;
  
// Function to return K such that changing
// all elements greater than K to K will
// make array sum N otherwise return -1
int findK(int arr[], int size, int N)
{
  
    // Sorting the array in increasing order
    sort(arr, arr + size);
    int temp_sum = 0;
  
    // Loop through all the elements of the array
    for (int i = 0; i < size; i++) {
        temp_sum += arr[i];
  
        // Checking if sum of array equals N
        if (N - temp_sum == arr[i] * (size - i - 1)) {
            return arr[i];
        }
    }
    return -1;
}
  
// Driver code
int main()
{
    int arr[] = { 3, 1, 10, 4, 8 };
    int size = sizeof(arr) / sizeof(int);
    int N = 16;
  
    cout << findK(arr, size, N);
  
    return 0;
}

chevron_right






                        filter_none









Java














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















// Java implementation of the approach  


import java.util.*; 


  


class GFG  


{ 


      


    // Function to return K such that changing  


    // all elements greater than K to K will  


    // make array sum N otherwise return -1  


    static int findK(int arr[], int size, int N)  


    {  


      


        // Sorting the array in increasing order  


        Arrays.sort(arr);  


        int temp_sum = 0;  


      


        // Loop through all the elements of the array  


        for (int i = 0; i < size; i++) 


        {  


            temp_sum += arr[i];  


      


            // Checking if sum of array equals N  


            if (N - temp_sum == arr[i] * (size - i - 1)) 


            {  


                return arr[i];  


            }  


        }  


        return -1;  


    }  


      


    // Driver code  


    public static void main (String[] args) 


    {  


        int []arr = { 3, 1, 10, 4, 8 };  


        int size = arr.length;  


        int N = 16;  


      


        System.out.print(findK(arr, size, N));  


    }  


} 


  


// This code is contributed by AnkitRai01 



















                        chevron_right







                        filter_none









Python














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















# Python3 implementation of the approach 


  


# Function to return K such that changing 


# all elements greater than K to K will 


# make array sum N otherwise return -1 


def findK(arr, size, N): 


  


    # Sorting the array in increasing order 


    arr = sorted(arr) 


    temp_sum = 0


  


    # Loop through all the elements of the array 


    for i in range(size): 


        temp_sum += arr[i] 


  


        # Checking if sum of array equals N 


        if (N - temp_sum == arr[i] * (size - i - 1)): 


            return arr[i] 


    return -1


  


# Driver code 


arr = [3, 1, 10, 4, 8] 


size = len(arr) 


N = 16


  


print(findK(arr, size, N)) 


  


# This code is contributed by mohit kumar 29 



















                        chevron_right







                        filter_none









C#














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















// C# implementation of the above approach 


using System; 


  


class GFG  


{ 


      


    // Function to return K such that changing  


    // all elements greater than K to K will  


    // make array sum N otherwise return -1  


    static int findK(int []arr, int size, int N)  


    {  


      


        // Sorting the array in increasing order  


        Array.Sort(arr);  


        int temp_sum = 0;  


      


        // Loop through all the elements of the array  


        for (int i = 0; i < size; i++) 


        {  


            temp_sum += arr[i];  


      


            // Checking if sum of array equals N  


            if (N - temp_sum == arr[i] * (size - i - 1)) 


            {  


                return arr[i];  


            }  


        }  


        return -1;  


    }  


      


    // Driver code  


    public static void Main() 


    {  


        int []arr = { 3, 1, 10, 4, 8 };  


        int size = arr.Length;  


        int N = 16;  


      


        Console.Write(findK(arr, size, N));  


    }  


} 


  


// This code is contributed by AnkitRai01 



















                        chevron_right







                        filter_none











Output:


4







Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.





    

        My Personal Notes
        arrow_drop_up
    

    

        
        

            
            
        

    


Recommended Posts:
SnehashishKalamkar
Check out this Author's contributed articles.
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on  the "Improve Article" button below.


Improved By :  mohit kumar 29, AnkitRai01