数据流中的中位数

数据流中的中位数

剑指 Offer 41. 数据流中的中位数

class MedianFinder {
public:
    /** initialize your data structure here. */
    
    //大顶堆 存较小值
    priority_queue<int> min_pq;
    //小根堆 存较大值
    priority_queue<int, vector<int>, greater<int>> max_pq;

    MedianFinder() {

    }
    
    void addNum(int num) {
        //先加入到较小值部分
        min_pq.push(num);
        //将较小值中最大值 移入较大值部分
        max_pq.push(min_pq.top());
        min_pq.pop();
        //平衡数量
        if(min_pq.size() < max_pq.size()){
            min_pq.push(max_pq.top());
            max_pq.pop();
        }
    }
    
    double findMedian() {
        //奇数个数
        if(min_pq.size()>max_pq.size()){
            return (double)min_pq.top();
        }else{//偶数个数
            return (double)(min_pq.top()+max_pq.top())/2;
        }
    }
};

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