Submission #1171413

#	Time	Username	Problem	Language	Result	Execution time	Memory
1171413		Zero_OP	Hacker (BOI15_hac)	C++20	100 / 100	57 ms	74572 KiB

hac

#include <bits/stdc++.h>

using namespace std;

#define FOR(i, l, r) for(int i = (l); i < (r); ++i)
#define ROF(i, r, l) for(int i = (r) - 1; i >= (l); --i)

#define mp make_pair
#define mt make_tuple
#define ff first
#define ss second

#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
#define pb push_back
#define eb emplace_back
#define sz(v) (int)v.size()
#define sum_of(v) accumulate(all(v), 0ll)
#define compact(v) v.erase(unique(all(v)), end(v))

#define dbg(x) "[" #x " = " << (x) << "]"

template<typename T>
      bool minimize(T& a, const T& b){
            if(a > b) return a = b, true;
            return false;
      }

template<typename T>
      bool maximize(T& a, const T& b){
            if(a < b) return a = b, true;
            return false;
      }

using ll = long long;
using db = double;
using ld = long double;
using ull = unsigned long long;

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;

using vi = vector<int>;
using vb = vector<bool>;
using vc = vector<char>;
using vl = vector<ll>;
using vd = vector<db>;

using vpi = vector<pi>;
using vpl = vector<pl>;

void setIO(){
      ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
      freopen("task.inp", "r", stdin);
      freopen("task.out", "w", stdout);
#endif // LOCAL
}

const int MAX = 5e5 + 5;

int N;
ll a[MAX * 2], b[MAX];

ll spt[20][MAX];

ll query_manual(int l, int r){
      if(l > r) return 0;
      return a[r] - a[l-1];
}

ll query_cyclic(int l, int r){
      if(l <= r) return query_manual(l, r);
      return query_manual(l, N) + query_manual(1, r);
}

ll query_max_manual(int l, int r){
      int k = 31 - __builtin_clz(r - l + 1);
      return max(spt[k][l], spt[k][r - (1 << k) + 1]);
}

ll query_max_cyclic(int l, int r){
      if(l <= r) return query_max_manual(l, r);
      return max(query_max_manual(l, N), query_max_manual(1, r));
}

signed main(){
      setIO();

      cin >> N;
      FOR(i, 1, N+1){
            cin >> a[i];
            a[i] += a[i-1];
      }

      if(N == 2){
            cout << *max_element(a+1, a+1+N) << '\n';
            return 0;
      }

      int len = (N/2);

      for(int i = 1, j = len; i <= N; ++i){
            spt[0][i] = query_cyclic(i, j);
            if(j == N) j = 1;
            else ++j;
      }

      for(int i = 1; (1 << i) <= N; ++i){
            for(int j = 1; j + (1 << i) - 1 <= N; ++j){
                  spt[i][j] = max(spt[i-1][j], spt[i-1][j+(1<<(i-1))]);
            }
      }

      ll ans = -1e18;
      FOR(i, 1, N+1){
            int l = (i == N ? 1 : i+1), r = (i > len ? i - len : i - len + N);
//            cout << dbg(l) << dbg(r) << dbg(query_max_cyclic(l, r)) << '\n';
            maximize(ans, a[N] - query_max_cyclic(l, r));
      }

      cout << ans << '\n';

      return 0;
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 40 / 40