import java.util.Random;
import java.util.Arrays;

class BinarySearch {
    public static int count = 0;
    
    protected static int searchRec(int[] a, int value, int low, int high) {
        count++;
        if (low > high) {
            return -1;
        }
        int mid = (high - low)/2 + low;
        if (value == a[mid]) {
            return mid;
        } else if (value < a[mid]) {
            return searchRec(a, value, low, mid - 1);
        } else {
            return searchRec(a, value, mid + 1, high);
        }
    }
    
    public static int search(int[] a, int value) {
        return searchRec(a, value, 0, a.length - 1);
    }
    
    public static void main(String[] args) {
        // try making ARRSZ bigger if you want
        // to see how fast binary search can be!
        final int ARRSZ = 10;
        Random r = new Random();

        // fill array with random values
        int[] data = new int[ARRSZ];
        for (int i = 0; i < ARRSZ; i++) {
            data[i] = r.nextInt();
        }

        // sort array
        Arrays.sort(data);

        // print
        System.out.println(Arrays.toString(data));

        // thing to search for
        int ridx = r.nextInt(data.length);
        int value = data[ridx];
    
        // search
        int idx = search(data, value);

        // print results
        System.out.println("Looking for value " + value + ".");
        System.out.println("Found at index = " + idx);
        System.out.println("Which is " + (idx == ridx ? "correct" : "incorrect"));

        // print number of steps-- pretty good!
        // count should be: ceil(log2(n))
        System.out.println(count);

        // search for thing not likely to be in array
        int idx2 = search(data, 0);
        System.out.println(idx2);
    }
}