Card game

#include <bits/stdc++.h>
using namespace std;
const int N = 1e6+5;

int main () {
    int ar[N];
    int n; cin >> n;
    for(int i = 0; i < n; i++) cin >> ar[i];

    if(n < 3) {
        cout << "0\n"; return 0;
    }
    if(n == 3) {
        cout << ar[1] << "\n"; return 0;
    }
    if(n == 4) {
        cout << max(ar[1], ar[2]) << "\n"; return 0;
    }
    
    int d0 = ar[1];
    int d1 = max(d0, ar[2]);
    int d2 = max(d1, ar[3]);

    for (int i = 4; i < n-1; ++i) {
        int cur = max(d2, d0 + ar[i]); // dp[i]
        d0 = d1;
        d1 = d2;
        d2 = cur;
    }

    cout << max({d0, d1, d2}) << '\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: ACCEPTED

Test 15

Verdict: ACCEPTED