Related Articles

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

• Difficulty Level : Medium
• Last Updated : 10 Jun, 2021

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:
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:

## C++

 `// C++ implementation of the approach` `#include ``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;``}`

## Java

 `// 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`

## Python

 `# 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`

## C#

 `// 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`

## Javascript

 ``
Output:
`4`

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

My Personal Notes arrow_drop_up