// This program demonstrates the use of a binary search method that returns an
// indication of the insertion point for data not yet in a sorted array.

import java.util.*;

public class BinarySearch {
    public static void main(String[] args) {
        int[] data = new int[20];
        Random r = new Random();
        for (int i = 0; i < data.length; i++) {
            data[i] = r.nextInt(50);
        }
        Arrays.sort(data);
        System.out.println("data = " + Arrays.toString(data));
        for (int i = 0; i < 20; i++) {
            System.out.println("index of " + i + " = " + binarySearch(data, i));
        }
    }
	
    // pre : list is sorted
    // post: returns the index of where value appears in the given array;
    //       returns -(insertion point) - 1 if not found
    public static int binarySearch(int[] list, int value) {
        int low = 0;
        int high = list.length - 1;
        while (low <= high) {
            int mid = (low + high) / 2;
            if (list[mid] == value) {
                return mid;
            } else if (list[mid] < value) {
                low = mid + 1;
            } else {
                high = mid - 1;
            }
        }
        return -low - 1;
    }
}