제출 #31683

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
31683		aome	Hacker (BOI15_hac)	C++14	100 / 100	349 ms	25612 KiB

hac

/*input
5
1 1 1 1 1
*/
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <utility>
#include <vector>
using namespace std;
#define sp ' '
#define endl '\n'
#define fi first
#define se second
#define mp make_pair
#define int long long
#define N 500005

int n;
int a[N];
int sum[N];
int f[4 * N];

int getsum(int l, int r) {
	return sum[r] - sum[l - 1];
}

int ceil(int x, int y) {
	int ret = x / y;
	if (x % y) ret++;
	return ret;
}

void update(int k, int l, int r, int pos, int val) {
	if (pos < l || r < pos) return;
	if (l == r) {
		f[k] = val;
		return;
	}
	int mid = (l + r) / 2;
	update(k * 2, l, mid, pos, val); update(k * 2 + 1, mid + 1, r, pos, val);
	f[k] = max(f[k * 2], f[k * 2 + 1]);
}

int get(int k, int l, int r, int L, int R) {
	if (r < L || R < l) return 0;
	if (L <= l && r <= R) return f[k];
	int mid = (l + r) / 2;
	return max(get(k * 2, l, mid, L, R), get(k * 2 + 1, mid + 1, r, L, R));
}

// https://oj.uz/problem/view/BOI15_hac
signed main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> a[i];
	for (int i = 1; i <= n; i++) sum[i] = sum[i - 1] + a[i];
	int ans = 0;
	for (int i = 1; i <= n; i++) {
		int last = i + n / 2 - 1;
		if (last <= n) {
			update(1, 1, n, i, getsum(i, last));
		}
		else {
			update(1, 1, n, i, getsum(i, n) + getsum(1, n / 2 - (n - i + 1)));
		}
	}
	for (int i = 1; i <= n; i++) {
		int last = i - n / 2;
		if (last < 0) last += n;
		int res = 0;
		if (last < i) {
			if (i != n)
				res = get(1, 1, n, i + 1, n);
			res = max(res, get(1, 1, n, 1, last));
		}
		else {
			res = get(1, 1, n, i + 1, last);
		}
		ans = max(ans, sum[n] - res);
	}
	cout << ans << endl;
}

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