剑指offer41-数据流的中位数-大顶堆小顶堆

class MedianFinder {
    
    List<Integer> list2;
    /** initialize your data structure here. */
    public MedianFinder() {
       
        list2=new ArrayList<>();
    }
    
    public void addNum(int num) {
       
        list2.add(num);
        Collections.sort(list2);
    }
    
    public double findMedian() {
        if(list2==null||list2.size()==0){
            return 0;
        }
        int x=list2.size();
        if(x%2==0){
            double a=list2.get(x/2);
            double b=list2.get(x/2-1);
            return (a+b)/2;
        }else{
            return list2.get((x-1)/2);
        }
    }
}

/**
 * Your MedianFinder object will be instantiated and called as such:
 * MedianFinder obj = new MedianFinder();
 * obj.addNum(num);
 * double param_2 = obj.findMedian();
 */