Card game

#include <iostream>

using namespace std;
typedef long long ll;

int n;
ll t[1000005];
ll dp[3][1000005];

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cin >> n;
	if (n < 3) {
		cout << "0\n";
		return 0;
	}
	for (int i = 0; i < n; ++i) {
		cin >> t[i];
	}
	// dp[i][0] = 0 for all i
	dp[0][1] = t[1];
	for (int i = 2; i < n; ++i) {
		dp[0][i] = t[i] + dp[2][i-1];
		dp[1][i] = dp[0][i-1];
		dp[2][i] = max(dp[1][i-1], dp[2][i-1]);
	}
	cout << max(dp[0][n-2], max(dp[1][n-2], dp[2][n-2])) << "\n";
	return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: UNKNOWN

Test 15

Verdict: UNKNOWN