Question.java

package Question9_5;

import java.util.ArrayList;

public class Question {
	public static int search(String[] strings, String str, int first, int last) {
		while (first <= last) {
			// Ensure there is something at the end
			while (first <= last && strings[last] == "") {
				--last;
			}
			if (last < first) {
				return -1; // this block was empty, so fail
			}
			int mid = (last + first) >> 1;
			while (strings[mid] == "") {
				++mid; // will always find one
			}
			int r = strings[mid].compareTo(str);
			if (r == 0) return mid;
			if (r < 0) {
				first = mid + 1;
			} else {
				last = mid - 1;
			}
		}
		return -1;
	}
		
	public static int search(String[] strings, String str) {
		if (strings == null || str == null) {
			return -1;
		}
		if (str == "") {
			for (int i = 0; i < strings.length; i++) {
				if (strings[i] == "") {
					return i;
				}
			}
			return -1;
			}
		return search(strings, str, 0, strings.length - 1);
	}
	
	public static void main(String[] args) {
        String[] stringList = {"apple", "", "", "banana", "", "", "", "carrot", "duck", "", "", "eel", "", "flower"};
		for (String s : stringList) {
        	System.out.println("<" + s + "> " + " appears at location " + search(stringList, s));
		}
	}
}