# Segregate even and odd numbers | Set 2

Given an array of integers, segregate even and odd numbers in the array. All the even numbers should be present first, and then the odd numbers.

Examples:

```Input : 1 9 5 3 2 6 7 11
Output : 6 2 3 5 7 9 11 1

Input : 1 3 2 4 7 6 9 10
Output : 10 2 6 4 7 9 3 1```

We have discussed one approach in Segregate Even and Odd numbers. In this post, a different simpler approach is discussed that uses an extra array.

Approach :

1. Start two pointers from left and right of the array.
2. Create a new array of same size as given.
3. If the element at left or right is even then put it in front of the array else at the end.

Implementation:

## C++

 `// CPP code to segregate even odd` `// numbers in an array` `#include ` `using` `namespace` `std;`   `// Function to segregate even odd numbers` `void` `arrayEvenAndOdd(``int` `arr[], ``int` `n) {`   `  ``int` `b[n];  ``// To store result` `  ``int` `k = 0, l = n - 1, i, j;` `  ``for` `(i = 0, j = n - 1; i < j; i++, j--) {`   `    ``if` `(arr[i] % 2 == 0) {` `      ``b[k] = arr[i];` `      ``k++;` `    ``} ``else` `{` `      ``b[l] = arr[i];` `      ``l--;` `    ``}`   `    ``if` `(arr[j] % 2 == 0) {` `      ``b[k] = arr[j];` `      ``k++;` `    ``} ``else` `{` `      ``b[l] = arr[j];` `      ``l--;` `    ``}` `  ``}`   `  ``// for i == j in case of odd length` `  ``b[i] = arr[i];`   `  ``// Printing segregated array` `  ``for` `(``int` `i = 0; i < n; i++) ` `     ``cout << b[i] << ``" "``;  ` `}`   `// Driver code` `int` `main() {` `  ``int` `arr[] = {1, 3, 2, 4, 7, 6, 9, 10};` `  ``int` `n = ``sizeof``(arr) / ``sizeof``(``int``);` `  ``arrayEvenAndOdd(arr, n);` `  ``return` `0;` `}`

## Java

 `// Java code to segregate even odd` `// numbers in an array` `import` `java.util.Arrays;`   `class` `arr` `{` `    ``// Function to segregate even odd numbers` `    ``static` `void` `arrayEvenAndOdd(``int` `arr[], ``int` `n) ` `    ``{` `        ``// To store result` `        ``int` `b[] = ``new` `int``[n]; ` `        ``int` `k = ``0``, l = n - ``1``, i, j;` `        ``for` `(i = ``0``, j = n - ``1``; i < j; i++, j--) ` `        ``{` `        `  `            ``if` `(arr[i] % ``2` `== ``0``) ` `            ``{` `                ``b[k] = arr[i];` `                ``k++;` `            ``} ` `            ``else` `            ``{` `                ``b[l] = arr[i];` `                ``l--;` `            ``}` `        `  `            ``if` `(arr[j] % ``2` `== ``0``)` `            ``{` `                ``b[k] = arr[j];` `                ``k++;` `            ``} ` `            ``else` `            ``{` `                ``b[l] = arr[j];` `                ``l--;` `            ``}` `        ``}` `    `  `        ``// for i == j in case of odd length` `        ``b[i] = arr[i];` `        `  `        ``// Printing segregated array` `        ``for` `(i = ``0``; i < n; i++) ` `        ``{` `            ``System.out.print(b[i] + ``" "``);` `        ``}` `    ``}` `    `  `    ``// Driver code` `    ``public` `static` `void` `main(String[] args) ` `    ``{` `        ``int` `arr[] = {``1``, ``3``, ``2``, ``4``, ``7``, ``6``, ``9``, ``10``};` `        ``int` `n = arr.length;` `        ``arrayEvenAndOdd(arr, n);` `    ``}` `}`   `// This code is contributed ` `// by Smitha Dinesh Semwal`

## Python3

 `# Python3 code to segregate even odd` `# numbers in an array`   `# Function to segregate even odd numbers` `def` `arrayEvenAndOdd(arr,n):  `   `    ``b ``=` `[``0``] ``*` `n  ``# To store result` `    ``k ``=` `0` `    ``l ``=` `n ``-` `1` `    ``i ``=` `0` `    ``j ``=` `n``-``1` `    ``while``(i < j):` `        ``if` `(arr[i] ``%` `2` `=``=` `0``):  ` `            ``b[k] ``=` `arr[i] ` `            ``k``+``=``1` `        ``else``:  ` `            ``b[l] ``=` `arr[i] ` `            ``l``-``=``1` `        ``if` `(arr[j] ``%` `2` `=``=` `0``):  ` `            ``b[k] ``=` `arr[j] ` `            ``k``+``=``1` `        ``else``:  ` `            ``b[l] ``=` `arr[j] ` `            ``l``-``=``1` `        ``i``+``=``1` `        ``j``-``=``1` `     `  ` `    `    ``# for i == j in case of odd length` `    ``b[i] ``=` `arr[i] `   `    ``# Printing segregated array` `    ``for` `i ``in` `range``(``0``, n): ` `        ``print``(b[i],end``=``" "``)  ` ` `    `# Driver code` `arr ``=`  `[``1``, ``3``, ``2``, ``4``, ``7``, ``6``, ``9``, ``10``]  ` `n ``=` `len``(arr)`   `arrayEvenAndOdd(arr, n)`   `# This code is contributed by` `# Smitha Dinesh Semwal`

## C#

 `// C# code to segregate even odd` `// numbers in an array` `using` `System;`   `class` `GFG {` `    `  `    ``// Function to segregate even odd numbers` `    ``static` `void` `arrayEvenAndOdd(``int` `[]arr, ``int` `n) ` `    ``{` `        `  `        ``// To store result` `        ``int` `[]b = ``new` `int``[n]; ` `        ``int` `k = 0, l = n - 1, i, j;` `        ``for` `(i = 0, j = n - 1; i < j; i++, j--) ` `        ``{` `        `  `            ``if` `(arr[i] % 2 == 0) ` `            ``{` `                ``b[k] = arr[i];` `                ``k++;` `            ``} ` `            ``else` `            ``{` `                ``b[l] = arr[i];` `                ``l--;` `            ``}` `        `  `            ``if` `(arr[j] % 2 == 0)` `            ``{` `                ``b[k] = arr[j];` `                ``k++;` `            ``} ` `            ``else` `            ``{` `                ``b[l] = arr[j];` `                ``l--;` `            ``}` `        ``}` `    `  `        ``// for i == j in case of odd length` `        ``b[i] = arr[i];` `        `  `        ``// Printing segregated array` `        ``for` `(i = 0; i < n; i++) ` `        ``{` `            ``Console.Write(b[i] + ``" "``);` `        ``}` `    ``}` `    `  `    ``// Driver code` `    ``public` `static` `void` `Main() ` `    ``{` `        ``int` `[]arr = {1, 3, 2, 4, 7, 6, 9, 10};` `        ``int` `n = arr.Length;` `        ``arrayEvenAndOdd(arr, n);` `    ``}` `}`   `// This code is contributed by vt_m.`

## Javascript

 ``

Output:

`10 2 6 4 7 9 3 1`

Time Complexity : O(n/2)
Auxiliary Space : O(n)

Feeling lost in the world of random DSA topics, wasting time without progress? It's time for a change! Join our DSA course, where we'll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 geeks!

Previous
Next