치킨 날다

#include <iostream>
#include <vector>
#include <algorithm>

struct chunk {
	unsigned int weight;
	unsigned int price;
};

using namespace std;

int main()
{
	unsigned int length = 0, needs = 0, weight = 0, price = 0, before = -1;
	vector<struct chunk> meatlist;

	cin >> length >> needs;
	for (int i = 0; i < length; ++i)
	{
		cin >> weight >> price;
		meatlist.push_back(chunk{ weight, price });
	}

	sort(meatlist.begin(), meatlist.end(), [](const auto& a, const auto& b) { return ((a.price < b.price) || (a.price == b.price) && (a.weight > b.weight)); });

	weight = price = 0;

	for (const auto& iter : meatlist)
	{
		if (weight < needs)
		{
			if (before == iter.price)
			{
				price += iter.price;
			}
			else
			{
				before = price = iter.price;
			}
		}
		else
		{
			if ((before != iter.price) && (price >= iter.price))
			{
				before = price = iter.price;
			}
		}
		weight += iter.weight;
	}

	if (weight < needs)
	{
		cout << -1 << endl;
	}
	else
	{
		cout << price << endl;
	}

	return 0;
}