// TranThienPhuc2657 // 20 ngay truoc khi toi ki thi Hoc sinh gioi Quoc gia 2025 - 2026, 25/12/2025. #include <bits/stdc++.h> using namespace std; #define file "CHONSO" #define TIME 1.0 * clock() / CLOCKS_PER_SEC #define ll long long #define pb push_back #define fi first #define se second #define pii pair <int, int> #define pll pair <ll, ll> #define Sz(x) ((int) (x).size()) #define getBit(mask, i) (((mask) >> (i)) & 1) template <typename T1, typename T2> bool mini(T1 &A, T2 B) {if (A > B) A = B; else return 0; return 1;} template <typename T1, typename T2> bool maxi(T1 &A, T2 B) {if (A < B) A = B; else return 0; return 1;} const int inf = 2e9 + 7; const ll linf = 1e18l + 7; const int mod = 1e9 + 7; const int N = 5e5 + 5; const int LOG = 30; int n, a[N]; ll sum[N + N]; int mid; struct Range_minimum_queries { ll mn[LOG][N + N]; void init() { for (int i = mid; i <= n + n; i++) mn[0][i] = sum[i] - sum[i - mid]; for (int lg = 1; (1 << lg) <= n + n; lg++) { for (int i = 1; i + (1 << lg) <= n + n; i++) { mn[lg][i] = min(mn[lg - 1][i], mn[lg - 1][i + (1 << (lg - 1))]); } } } ll get(int l, int r) { int lg = 31 - __builtin_clz(r - l + 1); return min(mn[lg][l], mn[lg][r - (1 << lg) + 1]); } } rmq; ll res = 0; // inp void inp() { cin >> n; for (int i = 1; i <= n; i++) cin >> a[i]; } // init void init() { for (int i = 1; i <= n; i++) sum[i] = sum[i - 1] + a[i]; for (int i = 1; i <= n; i++) sum[i + n] = sum[i + n - 1] + a[i]; mid = (n + 1) / 2; rmq.init(); } // proc void proc() { for (int i = 1; i < mid; i++) maxi(res, rmq.get(i + n, i + n + mid - 1)); for (int i = mid; i <= n; i++) maxi(res, rmq.get(i, i + mid - 1)); cout << res; } signed main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); if (fopen(file".inp", "r")) { freopen(file".inp", "r", stdin); freopen(file".out", "w", stdout); } inp(); init(); proc(); cerr << "Time elapsed: " << TIME << "s.\n"; return 0; }

hac.cpp: In function 'int main()':
hac.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen(file".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
hac.cpp:73:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen(file".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~