Method getPerms

java/Chapter 9/Question9_5/Question.java:7–27

(String str)

public class Question {

	public static ArrayList<String> getPerms(String str) {
		if (str == null) {
			return null;
		}
		ArrayList<String> permutations = new ArrayList<String>();
		if (str.length() == 0) { // base case
			permutations.add("");
			return permutations;
		}
	            
		char first = str.charAt(0); // get the first character
		String remainder = str.substring(1); // remove the first character
		ArrayList<String> words = getPerms(remainder);
		for (String word : words) {
			for (int j = 0; j <= word.length(); j++) {
				String s = insertCharAt(word, first, j);
				permutations.add(s);
			}
		}
		return permutations;
	}
	
	public static String insertCharAt(String word, char c, int i) {
		String start = word.substring(0, i);