PAT 1083. List Grades

用最大堆維護學生，周遊這個最大堆即可 -- top(); pop();

複雜度O(n)

代碼：

#include <string>
#include <iostream>
#include <queue>

using namespace std;

class Student
{
public:
	string name;
	string id;
	int grade;
	Student(string& _name, string& _id, int _grade): name(_name), id(_id), grade(_grade) {}
	friend bool operator< (const Student& a, const Student& b)
	{
		return a.grade < b.grade;
	}
};

int main()
{
	int n;
	priority_queue<Student> q;
	string name, id;
	int grade, grade1, grade2;
	bool none = true;

	cin >> n;
	while (n --)
	{
		cin >> name >> id >> grade;
		q.push(Student(name, id, grade));
	}
	cin >> grade1 >> grade2;
	while (q.empty() == false)
	{
		if (q.top().grade>=grade1 && q.top().grade<=grade2)
		{
			cout << q.top().name << " " << q.top().id << endl;
			none = false;
		}
		q.pop();
	}
	cout << (none? "NONE": "");

	return 0;
}