sort好用大家都知道的，废话不多说。

试过直接用数组，是会出现问题的，所以建议和容器一起用。

下面提供一种用法例子

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

struct Pearls
{
	int value;
	int amount;
};

bool cmp(struct Pearls a, struct Pearls b)
{
	if(a.value > b.value)
	{
		return true;
	}
	return false;
}

int main()
{
	int te;
	int i;
	int sum;
	int n;
	vector<struct Pearls> a(101);
	int max;
	
	scanf("%d", &te);
	while(te--)
	{
		scanf("%d", &n);
		for(i = 0; i < n; i++)
		{
			scanf("%d %d", &a[i].amount, &a[i].value);
		}
		
		sort(a.begin(), a.end(), cmp);
        for(i = 0; i < n; i++)
		{
			//printf("%d %d\n", a[i].amount, a[i].value);
		}
		max = a[0].value;
		//printf("%d\n", max);
		sum = max * (a[0].amount + 10);
		for(i = 1; i < n; i++)
		{
			if(a[i].value * (a[i].amount + 10) > max * a[i].amount)
			{
				sum += max * a[i].amount;
			}
			else
			{
				max = a[i].value;
				sum += max * (a[i].amount + 10);
			}
		}
		printf("%d\n", sum);
	}
	//scanf("%d");
}