Submission #677638

#	Time	Username	Problem	Language	Result	Execution time	Memory
677638		jhwest2	Seesaw (JOI22_seesaw)	C++17	100 / 100	98 ms	11648 KiB

seesaw

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

typedef long long ll;
typedef long double ld;
const int N = 202020;

int n; ll a[N], psum[N];
int main() {
    cin.tie(0); ios_base::sync_with_stdio(0);
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        psum[i] = psum[i - 1] + a[i];
    }
    vector<pair<ld, ld>> v(n);
    for (int i = 1; i <= n; i++) {
        int L = 0, R = i - 1;
        while (L < R) {
            int M = (L + R + 1) / 2;

            if ((ld)(psum[M + n + 1 - i] - psum[M]) / (n + 1 - i) <= (ld)psum[n] / n)
                L = M;
            else 
                R = M - 1;
        }
        v[i - 1].first = (ld)(psum[L + n + 1 - i] - psum[L]) / (n + 1 - i);

        L = 0; R = i - 1;
        while (L < R) {
            int M = (L + R) / 2;

            if ((ld)(psum[M + n + 1 - i] - psum[M]) / (n + 1 - i) >= (ld)psum[n] / n)
                R = M;
            else
                L = M + 1;
        }
        v[i - 1].second = (ld)(psum[L + n + 1 - i] - psum[L]) / (n + 1 - i);
    }
    sort(v.begin(), v.end());
    ld maxv = (ld)psum[n] / n;
    ld ans = 1e12;
    for (auto [x, y] : v) {
        ans = min(ans, maxv - x);
        maxv = max(maxv, y);
    }
    cout.precision(15);
    cout << fixed << ans;
}

• Subtask 1: 1 / 1
• Subtask 2: 33 / 33
• Subtask 3: 33 / 33
• Subtask 4: 33 / 33