Reverse a string

Write a method that takes in a String and returns the reversed version of the String.

Examples:
reverseString("abcde") -> "edcba"
reverseString("1") -> "1"
reverseString("") -> ""
reverse("madam") -> "madam"
reverse(null) -> null

Need a hand? Try out these hints, one at a time.

Quick hint to get things rolling

Use the StringBuilder class to build the reversed String.

A more detailed explanation

You will find the charAt(i) method of the String class and append() of the StringBuilder class useful. Remember - Strings in java are immutable. Each time a String is changed, a new copy of the String is made. For any changes to a String, using a StringBuilder object results in lower memory consumption and faster code.

Final hint! You should be able to code the problem on viewing this.

Iterate across the first String from str.length()-1 to 0, adding the character at index i (using .charAt(i)) to the new StringBuilder object with .append(i).
Finally, return the new String using the .toString() method of the StringBuilder object created earlier.

public static String reverseString(String str){
    String inputString = str;
    String outputString = null;
    
    
    
    return outputString;
}

This Coding Interview Question is available with an answer in the following programming languages :

Java

Python

Reverse a string

Quick hint to get things rolling

A more detailed explanation

Final hint! You should be able to code the problem on viewing this.

The interview prep tool you'll fall in love with!

This Coding Interview Question is available with an answer in the following programming languages :