WAP to reverse an array using recursion
Example
input: [1, 2, 3, 4]
output: [4, 3, 2, 1]
/**
* Reverse an array using recursion
* Method 1
* Implemented by MadhavBahl
* @date 18/01/2019
*/
function reverseArray (arr) {
if (arr.length === 1) return arr;
return reverseArray(arr.slice(1, arr.length)).concat([arr[0]]);
}
console.log (reverseArray([1, 2, 3, 4]));/**
* Reverse an array using recursion
* Method 1
* Implemented by MadhavBahl
* @date 18/01/2019
*/
function reverseArray (arr, startIndex, endIndex) {
if (startIndex >= endIndex) return arr;
let temp = arr[startIndex];
arr[startIndex] = arr[endIndex];
arr[endIndex] = temp;
reverseArray (arr, startIndex+1, endIndex-1);
}
let arr = [1, 2, 3, 4];
console.log (`Original Array: ${arr}`);
reverseArray (arr, 0, arr.length-1);
console.log (`Reversed Array: ${arr}`);import java.util.Scanner;
/**
* Reverse an array using recursion
* @author MadhavBahl
* @date 18/01/2019
*/
public class ReverseArray {
public static void reverse (int[] arr, int startIndex, int endIndex) {
if (startIndex >= endIndex) return;
// Swap equidistant elements from start and end
int temp = arr[startIndex];
arr[startIndex] = arr[endIndex];
arr[endIndex] = temp;
reverse (arr, startIndex+1, endIndex-1);
}
public static void main(String[] args) {
Scanner input = new Scanner (System.in);
System.out.println("/* ===== Sum of Array elements using recursion ===== */");
// Input the array
System.out.print("\nEnter the number of elements in the array: ");
int n = input.nextInt();
int arr[] = new int[n];
for (int i=0; i<n; i++) {
System.out.print("Enter arr[" + i + "]: ");
arr[i] = input.nextInt();
}
// Print the original array
System.out.print("Original Array: ");
for (int i=0; i<arr.length; i++)
System.out.print(arr[i] + " ");
// Reverse the array
reverse(arr, 0, arr.length-1);
// Print the reversed array
System.out.print("\nReversed Array: ");
for (int i=0; i<arr.length; i++)
System.out.print(arr[i] + " ");
}
}