855. 考场就座

855. 考场就座

题目链接：855. 考场就座

代码如下：

class ExamRoom 
{
public:
    ExamRoom(int n) :n(n) {}

    int seat() 
    {
        if (num.size() == 0)
        {
            num.insert(0);
            return 0;
        }

        int l = -1, r = 0, max = 0, insetNum = 0; //初始化左右节点，最大距离和要插入的值
        if (*num.begin() != 0) { max = *num.begin(); }
        for (auto it = num.begin();it != num.end();it++)
        {
            r = *it;
            if (max < (r - l) / 2)
            {
                max = (r - l) / 2;
                insetNum = l + (r - l) / 2;
            }
            l = r;
        }
        if (r != n - 1)
        {
            if (max < n - 1 - r)
            {
                insetNum = n - 1;
            }
        }
        num.insert(insetNum);
        return insetNum;
    }

    void leave(int p) 
    {
        num.erase(p);
    }

private:
    std::set<int> num;
    int n;
};

/**
 * Your ExamRoom object will be instantiated and called as such:
 * ExamRoom* obj = new ExamRoom(n);
 * int param_1 = obj->seat();
 * obj->leave(p);
 */