백준 11508 c++

문제에 나온 테스트케이스를 참고하여 알고리즘을 구현했더니 오히려 틀렸다. 가장 간단하게 내림차순으로 정렬해서 세개씩 그룹짓는게 정답이다.

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

using namespace std;

void input_milk(vector<int> &milk)
{
	int N, i, cost;

	cin >> N;
	for (i = 0; i < N; i++)
	{
		cin >> cost;
		milk.push_back(cost);
	}
	sort(milk.begin(), milk.end(), greater<>());

	return;
}

void find_answer(vector<int>& milk)
{
	int total = 0, temp_sum;
	deque<int> group;

	for (int i : milk)
	{
		group.push_back(i);
	}
	while (!group.empty())
	{
		temp_sum = 0;

		if (group.size() > 2)
		{
			/*temp_sum += group.front();
			group.pop_front();
			group.pop_back();
			temp_sum += group.back();
			group.pop_back();
			total += temp_sum;
			cout << total << "\n";*/

			temp_sum += group.front();
			group.pop_front();
			temp_sum += group.front();
			group.pop_front();
			group.pop_front();
			total += temp_sum;
			//cout << total << "\n";
		}
		else
		{
			total += group.front();
			group.pop_front();
			//cout << total << "\n";
		}
	}
	cout << total << "\n";

	return;
}

void find_answer2(vector<int>& milk)
{
	int total = 0;
	int i;

	for (i = 0; i < milk.size(); i++)
	{
		if (i % 3 == 2)
		{
			continue;
		}
		total += milk[i];
	}
	cout << total << "\n";

	return;
}

int main(void)
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	vector<int> milk;

	input_milk(milk);
	//find_answer(milk);
	find_answer2(milk);

	return 0;
}