Wheel of fortune

// ~/.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<int> num(n, 0);
    REP(i,0,n){
        cin >> num[i];
    }
    // r first
    vector<vector<long long>> res(n, vector<long long>(3, 0)); 
    res[0][0] = -num[0];
    res[0][1] = -1000000000;
    res[0][2] = -1000000000;
    REP(i, 1, n){
        res[i][0] = max(res[i-1][1], res[i-1][2]) - num[i];
        res[i][1] = max(res[i-1][0], res[i-1][2]);
        res[i][2] = max(res[i-1][1], res[i-1][0]) + num[i];
    }
    long long first = max(res[n-1][1], res[n-1][2]);

    // g second
    //vector<vector<long long>> res(n, vector<long long>(3, 0)); 
    res[0][0] = -1000000000;
    res[0][1] = 0;
    res[0][2] = -1000000000;
    REP(i, 1, n){
        res[i][0] = max(res[i-1][1], res[i-1][2]) - num[i];
        res[i][1] = max(res[i-1][0], res[i-1][2]);
        res[i][2] = max(res[i-1][1], res[i-1][0]) + num[i];
    }
    long long second = max(res[n-1][0], res[n-1][2]);
    second = max(second, first);


    // b last 
    //vector<vector<long long>> res(n, vector<long long>(3, 0)); 
    res[0][0] = -1000000000;
    res[0][1] = -1000000000;
    res[0][2] = num[0];
    REP(i, 1, n){
        res[i][0] = max(res[i-1][1], res[i-1][2]) - num[i];
        res[i][1] = max(res[i-1][0], res[i-1][2]);
        res[i][2] = max(res[i-1][1], res[i-1][0]) + num[i];
    }
    long long third = max(res[n-1][1], res[n-1][0]);


    cout << max(third, second) << endl;

    
    return 0;
}

Test 1

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Test 2

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