Submission #785069

#	Time	Username	Problem	Language	Result	Execution time	Memory
785069		Hanksburger	Hacker (BOI15_hac)	C++17	100 / 100	145 ms	10756 KiB

hac

#include <bits/stdc++.h>
using namespace std;
int seg[2000005], a[500005], b[500005], n, mx;
void build(int i, int l, int r)
{
    if (l==r)
    {
        if (l>n/2)
            seg[i]=b[n-1]-b[l-1]+b[l-n/2-1];
        else
            seg[i]=b[l+(n-1)/2]-b[l-1];
        return;
    }
    int m=(l+r)/2;
    build(i*2, l, m);
    build(i*2+1, m+1, r);
    seg[i]=min(seg[i*2], seg[i*2+1]);
}
int qry(int i, int l, int r, int ql, int qr)
{
    if (ql<=l && r<=qr)
        return seg[i];
    int m=(l+r)/2, res=1e9;
    if (l<=qr && ql<=m)
        res=min(res, qry(i*2, l, m, ql, qr));
    if (m<qr && ql<=r)
        res=min(res, qry(i*2+1, m+1, r, ql, qr));
    return res;
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> a[0];
    b[0]=a[0];
    for (int i=1; i<n; i++)
    {
        cin >> a[i];
        b[i]=b[i-1]+a[i];
    }
    build(1, 0, n-1);
    for (int i=0; i<n; i++)
    {
        if (i>n/2)
            mx=max(mx, min(qry(1, 0, n-1, i, n-1), qry(1, 0, n-1, 0, i-n/2-1)));
        else
            mx=max(mx, qry(1, 0, n-1, i, i+(n-1)/2));
    }
    cout << mx;
}

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