数据流中得中位数

链接说明

注意得点：
第一点：

import java.util.PriorityQueue;
public class Solution {
    PriorityQueue<Integer>  left=new PriorityQueue<>((n1,n2)->(n2-n1));////大根堆
    PriorityQueue<Integer>  right=new PriorityQueue<>((n1,n2)->(n1-n2));//小根堆
    int n;
    public void Insert(Integer num) {
        left.add(num);
        right.add(left.poll());
        if(right.size()-left.size()>1){
            left.add(right.poll());
        }


    }

    public Double GetMedian() {
        if(left.size()==right.size()){
            return (double) (left.poll()+right.poll())/2.0;
        }
        return (double)right.poll();
    }


}

为什么不行？比如你插入1，2，3
第二点：只能用peek(),不能用poll()

return (double)right.peek();
        }
         return (double) (left.peek()+right.peek())/2.0;