Submission #723553

#	Time	Username	Problem	Language	Result	Execution time	Memory
723553		drdilyor	Hacker (BOI15_hac)	C++17	0 / 100	1 ms	212 KiB

hac

#include<bits/stdc++.h>
using namespace std;
using ll = long long;


int nextPower2(int n) {
    n--;
    n |= n >> 1;
    n |= n >> 2;
    n |= n >> 4;
    n |= n >> 8;
    n |= n >> 16;
    return 1+n;
}

struct segtree {
    int n;
    vector<ll> t;
    segtree(int m) : n(nextPower2(m)), t(n*2, 1e18) {}
    void upd(int l, int r, ll x, int v, int tl, int tr) {
        if (l <= tl && tr <= r) {
            t[v] = min(t[v], x);
            return;
        }
        if (tr < l || r < tl) return;
        int mid = (tl+tr) / 2;
        upd(l, r, x, v*2, tl, mid);
        upd(l, r, x, v*2+1, mid+1, tr);
    }
    void upd(int l, int r, ll x) {
        upd(l, r, x, 1, 0, n-1);
    }
    ll query(int i) {
        ll res = t[i+=n];
        for (i /= 2; i >= 1; i /= 2)
            res = min(res, t[i]);
        return res;
    }
};

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int n; cin >> n;

    vector<int> arr(n*2);
    for (int i = 0; i < n; i++) {
        cin >> arr[i];
        arr[i+n] = arr[i];
    }

    segtree s(n*2);
    ll sum = accumulate(arr.begin(), arr.begin() + (n+1) / 2, 0ll);
    for (int l = 0, r = (n+1) / 2 - 1; l < n; l++, r++) {
        s.upd(l, r, sum);
        sum -= arr[l];
        if (r < n-1)sum += arr[r+1];
    }
    ll res = 0;
    for (int i = 0; i < n; i++)
        res = max(res, min(s.query(i), s.query(i+n)));
    cout << res << '\n';
}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 40