# Rotate all odd numbers right and all even numbers left in an Array of 1 to N

Last Updated : 26 Mar, 2021

Given a permutation arrays A[] consisting of N numbers in range [1, N], the task is to left rotate all the even numbers and right rotate all the odd numbers of the permutation and print the updated permutation.
Note: N is always even.
Examples:

Input: A = {1, 2, 3, 4, 5, 6, 7, 8}
Output: {7, 4, 1, 6, 3, 8, 5, 2}
Explanation:
Even element = {2, 4, 6, 8}
Odd element = {1, 3, 5, 7}
Left rotate of even number = {4, 6, 8, 2}
Right rotate of odd number = {7, 1, 3, 5}
Combining Both odd and even number alternatively.
Input: A = {1, 2, 3, 4, 5, 6}
Output: {5, 4, 1, 6, 3, 2}

Approach:

1. It is clear that the odd elements are always on even index and even elements are always laying on odd index.
2. To do left rotation of even number we choose only odd indices.
3. To do right rotation of odd number we choose only even indices.
4. Print the updated array.

Below is the implementation of the above approach:

## C++

 `// C++ program to implement` `// the above approach` `#include` `using` `namespace` `std;`   `// function to left rotate` `void` `left_rotate(``int` `arr[])` `{` `    ``int` `last = arr[1];` `    ``for` `(``int` `i = 3; i < 6; i = i + 2) ` `    ``{` `        ``arr[i - 2] = arr[i];` `    ``}` `    ``arr[6 - 1] = last;` `}`   `// function to right rotate` `void` `right_rotate(``int` `arr[])` `{` `    ``int` `start = arr[6 - 2];` `    ``for` `(``int` `i = 6- 4; i >= 0; i = i - 2) ` `    ``{` `        ``arr[i + 2] = arr[i];` `    ``}` `    ``arr[0] = start;` `}`   `// Function to rotate the array` `void` `rotate(``int` `arr[])` `{` `    ``left_rotate(arr);` `    ``right_rotate(arr);` `    ``for` `(``int` `i = 0; i < 6; i++) ` `    ``{` `        ``cout << (arr[i]) << ``" "``;` `    ``}` `}`   `// Driver code` `int` `main()` `{` `    ``int` `arr[] = { 1, 2, 3, 4, 5, 6 };`   `    ``rotate(arr);` `}`   `// This code is contributed by rock_cool`

## Java

 `// Java program to implement` `// the above approach`   `import` `java.io.*;` `import` `java.util.*;` `import` `java.lang.*;`   `class` `GFG {`   `    ``// function to left rotate` `    ``static` `void` `left_rotate(``int``[] arr)` `    ``{` `        ``int` `last = arr[``1``];` `        ``for` `(``int` `i = ``3``;` `            ``i < arr.length;` `            ``i = i + ``2``) {` `            ``arr[i - ``2``] = arr[i];` `        ``}` `        ``arr[arr.length - ``1``] = last;` `    ``}`   `    ``// function to right rotate` `    ``static` `void` `right_rotate(``int``[] arr)` `    ``{` `        ``int` `start = arr[arr.length - ``2``];` `        ``for` `(``int` `i = arr.length - ``4``;` `            ``i >= ``0``;` `            ``i = i - ``2``) {` `            ``arr[i + ``2``] = arr[i];` `        ``}` `        ``arr[``0``] = start;` `    ``}`   `    ``// Function to rotate the array` `    ``public` `static` `void` `rotate(``int` `arr[])` `    ``{` `        ``left_rotate(arr);` `        ``right_rotate(arr);` `        ``for` `(``int` `i = ``0``; i < arr.length; i++) {` `            ``System.out.print(arr[i] + ``" "``);` `        ``}` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `main(String[] args)` `    ``{` `        ``int` `arr[] = { ``1``, ``2``, ``3``, ``4``, ``5``, ``6` `};`   `        ``rotate(arr);` `    ``}` `}`

## Python3

 `# Python3 program for the above approach `   `# Function to left rotate ` `def` `left_rotate(arr):` `    `  `    ``last ``=` `arr[``1``]; ` `    ``for` `i ``in` `range``(``3``, ``len``(arr), ``2``):` `        ``arr[i ``-` `2``] ``=` `arr[i]` `        `  `    ``arr[``len``(arr) ``-` `1``] ``=` `last`   `# Function to right rotate ` `def` `right_rotate(arr):` `    `  `    ``start ``=` `arr[``len``(arr) ``-` `2``] ` `    ``for` `i ``in` `range``(``len``(arr) ``-` `4``, ``-``1``, ``-``2``):` `        ``arr[i ``+` `2``] ``=` `arr[i]` `        `  `    ``arr[``0``] ``=` `start`   `# Function to rotate the array ` `def` `rotate(arr):` `    `  `    ``left_rotate(arr)` `    ``right_rotate(arr) ` `    ``for` `i ``in` `range``(``len``(arr)): ` `        ``print``(arr[i], end ``=` `" "``)`   `# Driver code ` `arr ``=` `[ ``1``, ``2``, ``3``, ``4``, ``5``, ``6` `] `   `rotate(arr); `   `# This code is contributed by sanjoy_62`

## C#

 `// C# program to implement` `// the above approach` `using` `System;`   `class` `GFG{`   `// Function to left rotate` `static` `void` `left_rotate(``int``[] arr)` `{` `    ``int` `last = arr[1];` `    ``for``(``int` `i = 3;` `            ``i < arr.Length;` `            ``i = i + 2) ` `    ``{` `        ``arr[i - 2] = arr[i];` `    ``}` `    ``arr[arr.Length - 1] = last;` `}`   `// Function to right rotate` `static` `void` `right_rotate(``int``[] arr)` `{` `    ``int` `start = arr[arr.Length - 2];` `    ``for``(``int` `i = arr.Length - 4; ` `            ``i >= 0; i = i - 2)` `    ``{` `        ``arr[i + 2] = arr[i];` `    ``}` `    ``arr[0] = start;` `}`   `// Function to rotate the array` `public` `static` `void` `rotate(``int``[] arr)` `{` `    ``left_rotate(arr);` `    ``right_rotate(arr);` `    `  `    ``for``(``int` `i = 0; i < arr.Length; i++)` `    ``{` `        ``Console.Write(arr[i] + ``" "``);` `    ``}` `}`   `// Driver code` `public` `static` `void` `Main()` `{` `    ``int``[] arr = { 1, 2, 3, 4, 5, 6 };`   `    ``rotate(arr);` `}` `}`   `// This code is contributed by chitranayal`

## Javascript

 ``

Output:

`5 4 1 6 3 2`

Time Complexity: O(N)
Auxiliary Space: O(1)

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