Codeforces Round 840 (Div. 2) C. Another Array Problem

题目

思路：

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define fi first
#define se second
#define lson p << 1
#define rson p << 1 | 1
const int maxn = 1e6 + 5, inf = 1e9, maxm = 4e4 + 5;
const int N = 1e6;
// const int mod = 1e9 + 7;
const int mod = 998244353;
// int a[505][5005];
// bool vis[505][505];
// char s[505][505];
int a[maxn], b[maxn];
int vis[maxn];
string s;
int n, m;

struct Node{
    int val, id;
    bool operator<(const Node &u)const{
        return val < u.val;
    }
};
// Node c[maxn];

// int ans[maxn], pre[maxn];

//long long ? maxn ?

void solve(){
    int res = 0;
    int q, k;
    int sum = 0;
    int mx = 0;
    cin >> n;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        mx = max(mx, a[i]);
    }
    if(n >= 4){
        cout << n * mx << '\n';
    }
    else if(n == 2){
        cout << max(a[1] + a[2], 2LL * abs(a[1] - a[2])) << '\n';
    }
    else{
        res = max({a[1] + a[2] + a[3], 3LL * a[1], 3LL * a[3], 3LL * abs(a[1] - a[2]), 3LL * abs(a[2] - a[3])});
        cout << res << '\n';
    }
}
    
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    int T = 1;
    cin >> T;
    while (T--)
    {
        solve();
    }
    return 0;
}