#include<bits/stdc++.h> #define MASK(i) (1 << (i)) #define pub push_back #define all(v) v.begin(), v.end() #define compact(v) v.erase(unique(all(v)), end(v)) #define pii pair<int,int> #define fi first #define se second #define endl "\n" #define sz(v) (int)(v).size() #define dbg(x) "[" #x " = " << (x) << "]" #define vi vector<int> using namespace std; bool START_ALLOC; template<class T> bool minimize(T& a, T b){if(a > b) return a = b, true;return false;} template<class T> bool maximize(T& a, T b){if(a < b) return a = b, true;return false;} typedef long long ll; typedef long double ld; mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count()); ll rand(ll l, ll r){return uniform_int_distribution<ll>(l, r)(rng);} const int MAX = 1e6 + 15; int n, k; int a[MAX]; ll pref[MAX]; ll f[MAX]; void solve(){ cin >> n; for(int i = 1; i <= n; i++){ cin >> a[i]; pref[i] = pref[i-1] + a[i]; } for(int i = n+1; i <= 2*n; i++){ a[i] = a[i-n]; pref[i] = pref[i-1] + a[i]; } int k = (n + 1) / 2; for(int i = k; i <= 2*n; i++){ f[i] = pref[i] - pref[i-k]; } ll answer = 0; deque<int> dq; for(int i = 1; i <= 2*n; i++){ while(!dq.empty() && f[dq.back()] >= f[i]) dq.pop_back(); if(!dq.empty() && dq.front() <= i-k) dq.pop_front(); dq.push_back(i); if(i >= k) maximize(answer, f[dq.front()]); } cout << answer << endl; } bool END_ALLOC; signed main(){ ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0); #define task "task" cerr << "[Static Memory : " << fixed << setprecision(2) << (((&END_ALLOC) - (&START_ALLOC)) / (1024.0 * 1024.0)) << "mb]\n"; if(fopen(task".INP", "r")){ freopen(task".INP", "r", stdin); freopen(task".OUT", "w", stdout); } int t; t = 1; //cin >> t; while(t--) solve(); }

hac.cpp: In function 'int main()':
hac.cpp:74:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |         freopen(task".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
hac.cpp:75:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |         freopen(task".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~