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Javascript Program for Reversal algorithm for right rotation of an array

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  • Last Updated : 30 Mar, 2022
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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: 
 

Javascript




<script>
// JavaScript 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){
        let temp = arr[start];
        arr[start] = arr[end];
        arr[end] = temp;
        start++;
        end--;
    }
    return arr;
}
 
/* Function to right rotate arr[]
of size n by d */
function rightRotate(arr, d, n){
    arr = reverseArray(arr, 0, n-1);
    arr = reverseArray(arr, 0, d-1);
    arr = reverseArray(arr, d, n-1);
    return arr;
}
 
/* function to print an array */
function printArray( arr, size){
    for (let i = 0; i < size; i++)
        document.write( arr[i] + " ");
}
 
// driver code
let arr = [1, 2, 3, 4, 5,
                6, 7, 8, 9, 10];
     
let n = arr.length;
let k = 3;
     
arr = rightRotate(arr, k, n);
printArray(arr, n);
 
</script>


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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