Coffee shops

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

#define sqr(a) ((a) * (a))
#define pi 3.1415926535897932384626433832795

#define TASK "a"
#define MAXN 1000005
//#define CONTEST "1"

long long n, a[MAXN], ans[MAXN];
             
void Load()
{
	cin >> n;
	for(int i = 0; i < n; i++)
		cin >> a[i];
}

void Solve()
{
	if (n == 1)
	{ 
		cout << a[0];
		return;
	}

	if (n == 2) 
	{
		cout << min(a[0], a[1]);
		return;
	}
	if (n == 3) 
	{
		cout << min(a[1], a[0] + a[2]);
		return;
	}

	ans[0] = a[0];
	ans[1] = a[1];
	ans[2] = a[2] + a[0];

	for(int i = 3; i < n; i++)
	{
		long long m = min(ans[i-1], ans[i-2]);
		ans[i] = min(m, ans[i-3]) + a[i]; 
	}

//	for(int i = 0; i < n; i++)
//		cerr << ans[i] << " ";
	cout << min(ans[n-1], ans[n-2]);
}

int main()
{
#ifdef CONTEST
	freopen(TASK".in", "r", stdin);
	freopen(TASK".out", "w", stdout);
#endif
	ios::sync_with_stdio(0);
	Load();
	Solve();

	return 0;
}

Test 1

Verdict: UNKNOWN

Test 2

Verdict: UNKNOWN

Test 3

Verdict: UNKNOWN

Test 4

Verdict: UNKNOWN

Test 5

Verdict: UNKNOWN

Test 6

Verdict: UNKNOWN

Test 7

Verdict: UNKNOWN

Test 8

Verdict: UNKNOWN

Test 9

Verdict: UNKNOWN

Test 10

Verdict: UNKNOWN

Test 11

Verdict: UNKNOWN

Test 12

Verdict: UNKNOWN

Test 13

Verdict: UNKNOWN

Test 14

Verdict: UNKNOWN

Test 15

Verdict: UNKNOWN

Test 16

Verdict: UNKNOWN

Test 17

Verdict: UNKNOWN

Test 18

Verdict: UNKNOWN