import java.util.ArrayList;
import java.util.concurrent.ThreadLocalRandom;

/**
 * max heap
 *
 * @author fangchao
 */
public class Heap {
    private ArrayList<Integer> list = new ArrayList<>();

    public Heap() {
        list.add(null);
    }

    public void print() {
        System.out.println(list.toString());
    }

    public void add(Integer integer) {
        list.add(integer);
        int index = list.size() - 1;
        heapIt(index);
    }


    private void heapIt(int index) {
        int parent;
        while ((parent = index / 2) > 0) {
            int p = list.get(parent);
            int c = list.get(index);
            if (p < c) {
                list.set(parent, c);
                list.set(index, p);
                index = parent;
            } else {
                break;
            }
        }
    }

    public static void main(String[] args) {

        int size = 15;
        int min = 1;
        int max = 10;
        int testNum = 100;
        for (int j = 0; j < testNum; j++) {
            Heap heap = new Heap();
            for (int i = 0; i < size; i++) {
                int randomNum = ThreadLocalRandom.current().nextInt(min, max + 1);
                heap.add(randomNum);
            }
            heap.print();
        }
    }
}