# ZeroJudge - f448: 1316 - Supermarket
### 題目連結：https://zerojudge.tw/ShowProblem?problemid=f448
###### tags: `ZeroJudge` `貪心演算法（Greedy Algorithm）` `優先佇列（Priority Queue）`

#include <iostream>
#include <queue>
#include <algorithm>
using namespace std;

struct product {
	int profit, deadline;

	bool operator<(const product &other) {
		return this->deadline > other.deadline;
	}
} products[10000];

int main() {
	cin.sync_with_stdio(false); cin.tie(nullptr);
	int amount, maximumDeadline, nowProduct, profitSums;
	while (cin >> amount) {
		maximumDeadline = nowProduct = profitSums = 0;
		for (int i = 0; i < amount; ++i) {
			cin >> products[i].profit >> products[i].deadline;
			maximumDeadline = max(maximumDeadline, products[i].deadline);
		}
		sort(products, products + amount);
		priority_queue <int> PQ;
		for (int i = maximumDeadline; i; --i) {
			while (nowProduct < amount && products[nowProduct].deadline >= i)
				PQ.push(products[nowProduct].profit), ++nowProduct;
			if (!PQ.empty())
				profitSums += PQ.top(), PQ.pop();
		}
		cout << profitSums << '\n';
	}
}