# Represent N as sum of K even numbers

Given two integers N and K, the task is to represent N as sum of K even number. If it is not possible to represent the number, print -1.

Note: The representation may contain duplicate even numbers.

Examples:

Input: N = 6, K = 3
Output: 2 2 2
Explanation:
The given number 6 can be represented as 2 + 2 + 2 = 6

Input: N = 8, K = 2
Output: 2 6
Explanation:
The given number 3 can be represented as 2 + 6 = 8

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: To solve the problem mentioned above a simple solution is to maximise the occurrence of 2 which is the smallest even number. Necessary condition to represent N as sum of K numbers are:

• (K – 1) * 2 must be less than N.
• N – (K – 1) * 2 must be Even.

Below is the implementation of the above approach:

## C++

 `// C++ implementation to represent ` `// N as sum of K even numbers ` ` `  `#include ` `using` `namespace` `std; ` ` `  `// Function to print the representation ` `void` `sumEvenNumbers(``int` `N, ``int` `K) ` `{ ` `    ``int` `check = N - 2 * (K - 1); ` ` `  `    ``// N must be greater than equal to 2*K ` `    ``// and must be even ` `    ``if` `(check > 0 && check % 2 == 0) { ` `        ``for` `(``int` `i = 0; i < K - 1; i++) { ` `            ``cout << ``"2 "``; ` `        ``} ` `        ``cout << check; ` `    ``} ` `    ``else` `{ ` `        ``cout << ``"-1"``; ` `    ``} ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``int` `N = 8; ` `    ``int` `K = 2; ` ` `  `    ``sumEvenNumbers(N, K); ` `    ``return` `0; ` `} `

## Java

 `// Java implementation to represent ` `// N as sum of K even numbers ` `import` `java.util.*; ` ` `  `class` `GFG{ ` `     `  `// Function to print the representation ` `static` `void` `sumEvenNumbers(``int` `N, ``int` `K) ` `{ ` `    ``int` `check = N - ``2` `* (K - ``1``); ` ` `  `    ``// N must be greater than equal to 2 * K ` `    ``// and must be even ` `    ``if` `(check > ``0` `&& check % ``2` `== ``0``) ` `    ``{ ` `        ``for``(``int` `i = ``0``; i < K - ``1``; i++) ` `        ``{ ` `           ``System.out.print(``"2 "``); ` `        ``} ` `        ``System.out.println(check); ` `    ``} ` `    ``else` `    ``{ ` `        ``System.out.println(``"-1"``); ` `    ``} ` `} ` ` `  `// Driver Code ` `public` `static` `void` `main(String args[]) ` `{ ` `    ``int` `N = ``8``; ` `    ``int` `K = ``2``; ` ` `  `    ``sumEvenNumbers(N, K); ` `} ` `} ` ` `  `// This code is contributed by ANKITKUMAR34 `

## Python3

 `# Python3 implementation to represent ` `# N as sum of K even numbers ` ` `  `# Function to print the representation ` `def` `sumEvenNumbers(N, K): ` `     `  `    ``check ``=` `N ``-` `2` `*` `(K ``-` `1``) ` ` `  `    ``# N must be greater than equal to 2 * K ` `    ``# and must be even ` `    ``if` `(check > ``0` `and` `check ``%` `2` `=``=` `0``): ` `        ``for` `i ``in` `range``(K ``-` `1``): ` `            ``print``(``"2 "``, end ``=` `"") ` `             `  `        ``print``(check) ` `    ``else``: ` `        ``print``(``"-1"``) ` ` `  `# Driver Code ` `N ``=` `8` `K ``=` `2` `sumEvenNumbers(N, K) ` ` `  `# This code is contributed by ANKITKUMAR34 `

## C#

 `// C# implementation to represent ` `// N as sum of K even numbers ` `using` `System; ` ` `  `class` `GFG{ ` `     `  `// Function to print the representation ` `static` `void` `sumEvenNumbers(``int` `N, ``int` `K) ` `{ ` `    ``int` `check = N - 2 * (K - 1); ` ` `  `    ``// N must be greater than equal to ` `    ``//  2 * K and must be even ` `    ``if` `(check > 0 && check % 2 == 0) ` `    ``{ ` `        ``for``(``int` `i = 0; i < K - 1; i++) ` `        ``{ ` `           ``Console.Write(``"2 "``); ` `        ``} ` `        ``Console.WriteLine(check); ` `    ``} ` `    ``else` `    ``{ ` `        ``Console.WriteLine(``"-1"``); ` `    ``} ` `} ` ` `  `// Driver Code ` `static` `public` `void` `Main(String []args) ` `{ ` `    ``int` `N = 8; ` `    ``int` `K = 2; ` ` `  `    ``sumEvenNumbers(N, K); ` `} ` `} ` ` `  `// This code is contributed by 29AjayKumar `

Output:

```2 6
```

Time Complexity: O(K) My Personal Notes arrow_drop_up 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 : ANKITKUMAR34, 29AjayKumar