Submission #589683

#	Time	Username	Problem	Language	Result	Execution time	Memory
589683		penguinhacker	Hacker (BOI15_hac)	C++17	100 / 100	66 ms	13640 KiB

hac

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

#define ll long long
#define ar array

const int mxN=5e5;
int n, a[2*mxN], p[2*mxN+1], val[2*mxN+1];

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n;
	for (int i=0; i<n; ++i) {
		cin >> a[i];
		a[i+n]=a[i];
	}
	for (int i=0; i<2*n; ++i)
		p[i+1]=p[i]+a[i];
	for (int i=1; i+n/2<=2*n; ++i)
		val[i]=p[i+n/2]-p[i];
	int ans=0;
	/*for (int i=0; i<n; ++i) {
		int mx=0;
		for (int j=1; j<=(n+1)/2; ++j)
			mx=max(mx, val[i+j]);
		ans=max(ans, p[n]-mx);
	}*/
	deque<int> dq;
	for (int i=1; i<=n-1+(n+1)/2; ++i) {
		while(dq.size()&&val[i]>=val[dq.back()])
			dq.pop_back();
		dq.push_back(i);
		if (i-dq[0]>=(n+1)/2)
			dq.pop_front();
		assert(dq.size());
		if (i>=(n+1)/2)
			ans=max(ans, p[n]-val[dq[0]]);
	}
	cout << ans;
	return 0;
}

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