295.cpp

class MedianFinder {
    priority_queue<int> left;
    priority_queue<int, vector<int>, greater<int>> right;
public:
    /** initialize your data structure here. */
    MedianFinder() {
        left.push(INT_MIN);
        right.push(INT_MAX);
    }

    void addNum(int num) {
        int x = left.top();
        int y = right.top();
        if (num < x) {
            if (left.size() > right.size()) {
                left.pop();
                right.push(x);
            }
            left.push(num);
        } else if (num < y) {
            if (left.size() == right.size()) {
                left.push(num);
            } else {
                right.push(num);
            }
        } else {
            if (left.size() == right.size()) {
                right.pop();
                left.push(y);
            }
            right.push(num);
        }
    }

    double findMedian() {
        if (left.size() != right.size()) {
            return left.top();
        } else {
            return (double(left.top()) + right.top()) / 2;
        }
    }
};

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