Submission #772328

#	Time	Username	Problem	Language	Result	Execution time	Memory
772328		SLin25	Hacker (BOI15_hac)	C++14	100 / 100	43 ms	10628 KiB

hac

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

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int n; cin >> n;
    int arr[n];
    int pref[n+1]{};
    int k = (n + 1) / 2;
    for (int i = 0; i < n; i++) {
        cin >> arr[i];
    }
    for (int i = 1; i <= n; i++) {
        pref[i] += pref[i-1] + arr[i-1];
    }
    int val[n]; //segment ending at index
    for (int i = 0; i < n; i++) {
        int prev = i - k + 1;
        int tmp = 0;
        if (prev < 0) {
            tmp = pref[i+1] + pref[n] - pref[n + prev];
        } else {
            tmp = pref[i+1] - pref[prev];
        }
        val[i] = tmp;
    }
    deque<pair<int, int>> q;
    int ans = 0;
    for (int i = 0; i < k; i++) {
        while (!q.empty() && q.back().first > val[i]) {
            q.pop_back();
        }
        q.push_back({val[i], i});
    }

    ans = max(ans, q.front().first);

    for (int i = k; i < n; i++) {
        while (!q.empty() && q.back().first > val[i]) {
            q.pop_back();
        }
        q.push_back({val[i], i});
        if (q.front().second == i - k) q.pop_front();
        ans = max(ans, q.front().first);
    }
    for (int i = 0; i < k; i++) {
        while (!q.empty() && q.back().first > val[i]) {
            q.pop_back();
        }
        q.push_back({val[i], i});
        if (q.front().second == i - k + n) q.pop_front();
        ans = max(ans, q.front().first);
    }

    cout << ans << '\n';
}

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