Submission #633179

#	Time	Username	Problem	Language	Result	Execution time	Memory
633179		Alma	Hacker (BOI15_hac)	C++17	0 / 100	1 ms	212 KiB

hac

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

#define fi first
#define se second
using ll = long long;
using ii = pair<int,int>;

const int INF = 1e9;
const ll LLINF = 1e18;
using vi = vector<int>;
using vvi = vector<vi>;

void setIO (string fileName) {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    if (fileName != "std") {
        freopen((fileName + ".in").c_str(), "r", stdin);
        freopen((fileName + ".out").c_str(), "w", stdout);
    }
}

ll ask (int l, int r, vector<ll>& p) {
	return p[r] - p[l-1];
}

int main() {
    setIO("std");

    int n;
	cin >> n;
	vector<ll> a(3*n), p(3*n), seg(n);
	vi l(n), r(n);

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

	p[0] = a[0];
	for (int i = 1; i < 3*n; i++) {
		p[i] = p[i-1] + a[i];
	}

	int d = n/2;
	for (int i = 0; i < n; i++) {
		int l1 = n+i-d+1, l2 = n+i;
		int r1 = n+i, r2 = n+i+d-1;
		int res = 0;
		for (int cnt = 0; cnt < 30; cnt++) {
			int x1 = ask(l1, r1, p);
			int x2 = ask(l2, r2, p);
			if (x1 > x2) {
				l2 = (l1+l2) / 2;
				r2 = (r1+r2) / 2;
			} else {
				l1 = (l1+l2) / 2;
				r1 = (r1+r2) / 2;
			}
			res = max(res, max(x2, x2));
		}
		seg[i] = res;
		l[i] = l1;
		r[i] = r1;
	}

	ll ans = 0, mx = ask(n, 2*n-1, p);
	for (int i = 0; i < n; i++) {
		ans = max(ans, mx - seg[(i + n/2) % n]);
		if (n % 2 == 1) ans = max(ans, mx - seg[(i + (n+1)/2) % n]);
	}
	cout << ans << '\n';

    return 0;
}

Compilation message (stderr)

hac.cpp: In function 'void setIO(std::string)':
hac.cpp:18:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |         freopen((fileName + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
hac.cpp:19:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |         freopen((fileName + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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