/**
* Implements binary search over an unordered list
* Hence, the code needs to backtrack when it cannot find the target.
* Generally, this is a really silly thing to do
**/
public class BacktrackingSearch
{
    /**
     * The data to be searched
     **/
    private int[] data = {1, 998, 10, 997, 11, 996, 100, 995, 101, 994, 110, 993, 111, 992, 1000};

    /**
     * A counter of the number of steps the search required
     **/
    private int steps;

    /**
     * Default constructor ... nothing to do
     **/
    public BacktrackingSearch()
    {
    }

    /**
     * The public searhc method.
     * Thsi sets private variable steps to 0, then begins a search.
     * Note that steps will be incorrect is there are two concurrent searches.
     **/
    public boolean search(int target)
    {
	steps=0;
	return iSearch(target, 0, data.length-1, 1);
    }

    /**
     * Implement Binary search, recursively on internal array of ints
     * @param target the item to be found
     * @param lo the bottom of the range being searched
     * @param hi the top of the range being searched
     * @param depth the depth of the stack
     * @return true if the target was found
     */
    private boolean iSearch(int target, int lo, int hi, int depth)
    {
	// increment steps.  Every class to iSearch increments ...
	steps++;
	System.out.print(steps);
	// a base case.
	if (lo>hi) { System.out.println(); return false; }
	int mid = (lo+hi)/2;
	// Print information about what is being searched
	System.out.println(" " + target + " " + data[mid] + " " + lo + " " + hi + " " + depth);
	// Found it!!
	if (data[mid]==target) return true;
	// Check the upper half of the items to be searched
	if (iSearch(target, mid+1, hi, depth+1))
	{
	    return true;
	}
	else
	{
	    // if the number was not in the upper half, check the lower half
	    return iSearch(target, lo, mid-1, depth+1);
	}
    }

    public static void main(String[] args)
    {
	BacktrackingSearch bs = new BacktrackingSearch();
	int[] tgts = {10};
	for (int ii : tgts)
	    System.out.println(bs.search(ii) ? "Found" : "Not Found");
    }

}