Card game

#include <bits/stdc++.h>
using namespace std;

#define all(x)  begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sz(x)   (int)(x).size()                                 // signed size: avoids the unsigned .size() wrap bug

using ll  = long long;
using pii = pair<int,int>;
using vi  = vector<int>;

#ifdef LOCAL                                                    // compile with -DLOCAL to enable, silent on the judge
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "] = ", dbg_out(__VA_ARGS__)
template<class T> void dbg_out(T x) { cerr << x << '\n'; }
template<class T, class... R> void dbg_out(T x, R... r) { cerr << x << ", "; dbg_out(r...); }
#else
#define dbg(...)
#endif

int main() {
    cin.tie(0)->sync_with_stdio(0);                             // never mix with scanf/printf after this
    int n; cin >> n; 
    // int n,m; cin >> n >> m; 
    vi a(n); for (auto &x : a) cin >> x;


    vi dp(n+1, 0); 
    for (int i = 3; i < n + 1; i++)
    {
        dp[i] = max(dp[i-1], dp[i-3] + a[i-2]);
        // cout << dp[i];
    }
    cout << dp[n];
    
    // cout << ;
    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