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# Change K elements so that (a1^2 + a2^2 + …+ aN^2 ) <= (a1 + a2 +…+ aN) becomes true

• Difficulty Level : Basic
• Last Updated : 13 Apr, 2021

Given an array Arr of size N. The task is to tell whether it is possible to change at most K elements of this sequence to arbitrary positive integers in such a way that the below condition holds. Examples:

```Input:N = 2, Arr[] = {1, 2}, K = 2
Output: Possible
(As A can be change to 1)

Input: N = 2, Arr[] = {5, 6}, K = 1
Output: Not Possible
(As we can only change 1 element to any arbitrary number
and after changing it doesn't satisfy above condition) ```

Approach: When all the elements of the array becomes equal to 1 then only the given equation can be satisfied, else not.

1. Traverse the array and count the number of 1.
2. If K >= (size of array i.e N – count) then return true, Else return false.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of above approach``#include ``using` `namespace` `std;` `// Function that will tell``// whether it is possible or Not``int` `Series(``int` `Arr[], ``int` `N, ``int` `K)``{``    ``int` `count = 0;``    ``for` `(``int` `i = 0; i < N; i++)``        ``if` `(Arr[i] == 1)``            ``count++;` `    ``if` `(K >= (N - count))``        ``return` `1;``    ``else``        ``return` `0;``}` `// Driver code``int` `main()``{``    ``int` `Arr[] = { 5, 1, 2 };``    ``int` `N = ``sizeof``(Arr) / ``sizeof``(Arr);``    ``int` `K = 2;` `    ``// Calling function.``    ``int` `result = Series(Arr, N, K);` `    ``if` `(result == 1)``        ``cout << ``"Possible"``;``    ``else``        ``cout << ``"Not Possible"``;``    ``return` `0;``}`

## Java

 `//Java  implementation of above approach` `import` `java.io.*;` `class` `GFG {``    ` `// Function that will tell``// whether it is possible or Not``static` `int` `Series(``int` `Arr[], ``int` `N, ``int` `K)``{``    ``int` `count = ``0``;``    ``for` `(``int` `i = ``0``; i < N; i++)``        ``if` `(Arr[i] == ``1``)``            ``count++;` `    ``if` `(K >= (N - count))``        ``return` `1``;``    ``else``        ``return` `0``;``}` `// Driver code``    ``public` `static` `void` `main (String[] args) {``    ``int` `Arr[] = { ``5``, ``1``, ``2` `};``    ``int` `N = Arr.length;``    ``int` `K = ``2``;``    ``// Calling function.``    ``int` `result = Series(Arr, N, K);``    ``if` `(result == ``1``)``            ``System.out.println (``"Possible"``);``    ``else``            ``System.out.println( ``"Not Possible"``);``        ` `    ``}``//This Code is Contributed by ajit   ``}`

## Python3

 `# Python implementation of``# above approach` `# Function that will tell``# whether it is possible or Not``def` `Series(Arr, N, K):``    ``count ``=` `0``    ``for` `i ``in` `range``(N):``        ``if` `Arr[i] ``=``=` `1``:``            ``count ``+``=` `1``    ``if` `K >``=` `(N ``-` `count):``        ``return` `1``    ``return` `0` `# Driver code``Arr ``=` `[``5``, ``1``, ``2``]``N ``=` `len``(Arr)``K ``=` `2` `result ``=` `Series(Arr, N, K)``if` `result ``=``=` `1``:``    ``print``(``"Possible"``)``else``:``    ``print``(``"Not Possible"``)` `# This code is contributed``# by Shrikant13`

## C#

 `//C# implementation of above approach` `using` `System;` `public` `class` `GFG{``    ` `        ` `// Function that will tell``// whether it is possible or Not``static` `int` `Series(``int` `[]Arr, ``int` `N, ``int` `K)``{``    ``int` `count = 0;``    ``for` `(``int` `i = 0; i < N; i++)``        ``if` `(Arr[i] == 1)``            ``count++;` `    ``if` `(K >= (N - count))``        ``return` `1;``    ``else``        ``return` `0;``}` `// Driver code``    ` `    ``static` `public` `void` `Main (){``    ``int` `[]Arr = { 5, 1, 2 };``    ``int` `N = Arr.Length;``    ``int` `K = 2;``    ``// Calling function.``    ``int` `result = Series(Arr, N, K);``    ``if` `(result == 1)``            ``Console.WriteLine (``"Possible"``);``    ``else``            ``Console.WriteLine( ``"Not Possible"``);``        ` `    ``}``//This Code is Contributed by akt_mit``}`

## PHP

 `= (``\$N` `- ``\$count``))``        ``return` `1;``    ``else``        ``return` `0;``}` `// Driver code``\$Arr` `= ``array``( 5, 1, 2 );``\$N` `= sizeof(``\$Arr``);``\$K` `= 2;` `// Calling function.``\$result` `= Series(``\$Arr``, ``\$N``, ``\$K``);` `if` `(``\$result` `== 1)``    ``echo` `"Possible"``;``else``    ``echo` `"Not Possible"``;` `// This code is contributed``// by Sach_Code``?>`

## Javascript

 ``
Output:
`Possible`

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