优先级队列（大堆的实现）

优先级队列的基本实现（大堆）

public class ProiorityQueue {
    private int[] array = new int[10];
    private int size = 0;
    //向上调整
    private void adjustUp(){
        int index = size;
        while (index != 0){
            int parent = (index-1) / 2;
            if (array[index] <= array[parent]){
                break;
            }else {
                swap(parent, index);
                index = parent;
            }
        }
    }
    //交换值
    private void swap(int parent, int index) {
        int num = array[parent];
        array[parent] = array[index];
        array[index] = num;
    }
    //放元素
    public void put(int val){
        if(size == array.length){
            throw new RuntimeException("堆满");
        }

        array[size] = val;
        adjustUp();
        size++;
    }
    //取元素
    public int take(){
        if(size == 0){
            throw new RuntimeException("堆空");
        }
        int val = array[0];
        array[0] = array[size-1];
        size--;
        adjustDown();
        return val;
    }
    //向下调整
    private void adjustDown() {
        int index = 0;
        while (2 * index +1 < size){
            int max = 2 * index + 1;
            if(max + 1 < size && array[max] < array[max+1]){
                max++;
            }
            if(array[index] < array[max]){
                swap(index, max);
                index = max;
            }else {
                break;
            }
        }
    }
}