1.3 URLify: Write a method to replace all spaces in a string with '%20: You may assume that the string has sufficient space at the end to hold the additional characters, and that you are given the "true" length of the string. (Note: If implementing in Java, please use a character array so that you can perform this operation in place.)
EXAMPLE
Input: "Mr John Smith "J 13
Output: "Mr%20J ohn%20Smith"

public String replace(String str) {
    String[] words = str.split(" ");
    StringBuilder sentence = new StringBuilder(words[0]);

    for (int i = 1; i < words.length; ++i) {
        sentence.append("%20");
        sentence.append(words[i]);
    }

    return sentence.toString();
}