Given an array, right rotate it by k elements.
After K=3 rotation
Examples:
Input: arr[] = {1, 2, 3, 4, 5,
6, 7, 8, 9, 10}
k = 3
Output: 8 9 10 1 2 3 4 5 6 7
Input: arr[] = {121, 232, 33, 43 ,5}
k = 2
Output: 43 5 121 232 33
Note : In the below solution, k is assumed to be smaller than or equal to n. We can easily modify the solutions to handle larger k values by doing k = k % n
Algorithm:
rotate(arr[], d, n) reverseArray(arr[], 0, n-1) ; reverse(arr[], 0, d-1); reverse(arr[], d, n-1);
Below is the implementation of above approach:
PHP
<?php // PHP program for right rotation of // an array (Reversal Algorithm)/*Function to reverse arr[] from index start to end*/function reverseArray(&$arr, $start, $end){ while ($start < $end) { $temp = $arr[$start]; $arr[$start] = $arr[$end]; $arr[$end] = $temp; $start++; $end--; }}/* Function to right rotate arr[]of size n by d */function rightRotate(&$arr, $d, $n){ reverseArray($arr, 0, $n - 1); reverseArray($arr, 0, $d - 1); reverseArray($arr, $d, $n - 1);}/* function to print an array */function printArray(&$arr, $size){ for ($i = 0; $i < $size; $i++) echo $arr[$i] . " ";}// Driver code$arr = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);$n = sizeof($arr);$k = 3;rightRotate($arr, $k, $n);printArray($arr, $n);// This code is contributed by ita_c?> |
Output:
8 9 10 1 2 3 4 5 6 7
Time Complexity: O(N)
Auxiliary Space: O(1)
Please refer complete article on Reversal algorithm for right rotation of an array for more details!
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