Question

Write a recursive method (no loops) which takes a String and reverses it. You should call this method reverseString. The method should take a String and return the String reversed.

Input
n, where n is a String
Sample Input

Hello
Output

The String reversed
Sample Output

olleH

Answer 1

The question involves creating a recursive method called reverseString that takes a String and returns it in reverse order, a concept under the Computers and Technology subject typically encountered by High School students.

Step-by-step explanation:

The task is to write a recursion-based method to reverse a string without using loops. In the field of Computers and Technology, specifically in programming, this is an example of systematizing a problem into smaller subproblems, which is a foundational concept in understanding recursion.

Java Implementation

The reverseString method can be defined in Java as follows:

public String reverseString(String n) {
if (n.isEmpty()) {
return n;
}
return reverseString(n.substring(1)) + n.charAt(0);
}

This method takes a String n as its parameter. If n is empty, it returns n as the base case of recursion. Otherwise, it recursively calls itself with the substring of n starting from the second character, and then appends the first character of n to the result of the recursion.

Sample usage:

String original = "Hello";
String reversed = reverseString(original);
System.out.println(reversed); // Outputs: olleH

The provided code is a clear example of how recursion can be applied to reverse a string. It demonstrates breaking down the problem, handling the base case, and recursively calling the function until all characters are processed and appended in reverse order.