Javascript Program for Reversal algorithm for right rotation of an array
Last Updated : 23 Sep, 2024
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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 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;
}
// 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);
console.log(arr.join(" "));
Output
8 9 10 1 2 3 4 5 6 7
Complexity Analysis:
- Time Complexity: O(N)
- Auxiliary Space: O(1)
Please refer complete article on Reversal algorithm for right rotation of an array for more details!
