private static List<Integer> list = new ArrayList<>();

/**

public static void add(int data) {

list.add(data);

int size = list.size();

for (int i = 0; i < size; i++) {

int index = i;

while (list.get(index) > list.get((index - 1) / 2)) {

//父子交换

swap(list, index, (index - 1) / 2);

index = (index - 1) / 2;

}

}

swap(list,0,--size);

//重新排序

while (size > 0) {

heapify(list, 0, size);

swap(list, 0, --size);

}

}

/**

public static int poll() {

if (list.size() == 0) {

return 0;

}

int res = list.remove(list.size()-1);

return res;

}

public static void swap(List<Integer> list, int a, int b) {

int tmp = list.get(a);

list.set(a, list.get(b));

list.set(b, tmp);

}

public static void heapify(List<Integer> list, int index, int size) {

int left = index * 2 + 1;

while (left < size) {

int maxNum = left + 1 < size && list.get(left + 1) > list.get(left) ? left + 1 : left;

maxNum = list.get(maxNum) > list.get(index) ? maxNum : index;

if (maxNum == index) {

break;

}

int tmp = list.get(index);

list.set(index, list.get(left));

list.set(maxNum, tmp);

index = maxNum;

left = index * 2 + 1;

}

}

public static int peek() {

int res = list.get(list.size()-1);

return res;

}

public static void main(String[] args) {

add(1);

add(3);

add(2);

add(5);

add(4);

System.out.println(poll());

System.out.println(poll());

add(8);

add(9);

System.out.println(peek());

System.out.println(poll());

}