Card game

// ~/.vim/cpp_template.cpp
#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

#define REP(i,a,b) for (int i = a; i < b; i++)

using namespace std;

template <typename T>
void pV(const std::vector<T>& vec, const std::string& label = "Vector") {
    std::cout << label << ": [ ";
    for (const auto& elem : vec) {
        std::cout << elem << " ";
    }
    std::cout << "]" << std::endl;
}


using namespace std;


void dfs(int s, vector<bool> *visited, vector<int> (*adj)[]) {
    if ((*visited)[s]) return;
    (*visited)[s] = true;
    // process node s


    for (auto u: (*adj)[s]) {
        dfs(u, visited, adj);
    }
}
/*
vector<int> adj[N];                                                          
vector<bool> visited(N, false);
int u, v;
for(int i = 0; i < M;i++){
    cin >> u >> v;
    u--;
    v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
}
*/

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    // Your code starts here
    int n;
    cin >> n;

    vector<long long> v(n, 0);
    REP(i, 0, n){
        cin >> v[i];
    }


    if(n < 3){
        cout << 0;
        return 0;
    }

    vector<long long> r(n,0);
    r[0] = 0;
    REP(i, 1, n-1){
        if(i < 2){
            r[i] = v[1];
        }else if(i<3){
            r[i] = max(v[i], r[i-1]);
        }else if(i<4){
            r[i] = max(v[i], max(r[i-2], r[i-1]));
        }else{
            r[i] = max(r[i-3] + v[i], max(r[i-2], r[i-1]));
        }
    }
    cout << r[n-2];

    
    
    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