295. Find Median from Data Stream

295. Find Median from Data Stream295. Find Median from Data Stream

class MedianFinder {
public:
    /** initialize your data structure here. */
    MedianFinder() {
        
    }
    
    void addNum(int num) {
        if(even)
        {
            large.push(num);
            small.push(large.top());
            large.pop();
        }else
        {
            small.push(num);
            large.push(small.top());
            small.pop();
        }
        even = !even;     
    }
    
    double findMedian() {
        if(even)
            return static_cast<double>((small.top() + large.top())) / 2;
        else
            return small.top();
    }
private:
    priority_queue<int> small;
    priority_queue<int, vector<int>, std::greater<int>> large;
    bool even = true;
};

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

small存放小的一半，large存放大的一半，保证small的大小永远等于large.size()或large.size() + 1