Java PriorityQueue（优先队列）实现大顶堆和小顶堆

Java PriorityQueue类是一种队列数据结构实现
它与遵循FIFO（先进先出）算法的标准队列不同。

//默认为小顶堆
PriorityQueue<Integer> minHeap = new PriorityQueue<>(k, (a,b)->a-b);
 
PriorityQueue<Integer> minHeap = new PriorityQueue<>(k, new Comparator<Integer>() {
           @Override
           public int compare(Integer a, Integer b) {
               return a - b;
           }
 });

//大顶堆

PriorityQueue<Integer> maxHeap = new PriorityQueue<>(k, (a,b)->b-a);
 
PriorityQueue<Integer> maxHeap = new PriorityQueue<>(k, new Comparator<Integer>() {
           @Override
           public int compare(Integer a, Integer b) {
               return b - a;
           }
 });