Submission #698365

#	Time	Username	Problem	Language	Result	Execution time	Memory
698365		Duy_e	Seesaw (JOI22_seesaw)	C++14	0 / 100	0 ms	212 KiB

seesaw

#include <bits/stdc++.h>
#define ll long long
#define pii pair <ll, ll>
#define st first
#define nd second
#define rep(i, n, m) for (ll i = n; i <= m; i ++)
#define rrep(i, n, m) for (ll i = n; i >= m; i --)
#define file "test"
using namespace std;

const long long N = 2e5 + 7;
const long long INF = 1e18;
const long long MOD = 2e9 + 11;
const long long base = 311;
const long double eps = 1e-10;
ll n, a[N];

bool is_smaller(pii x, pii y) {
    return x.st / x.nd <= y.st / y.nd;
}

long double checkL(int l, int r, int n) {
    ll s = 0;
    rep(i, 1, n) s += a[i];
    pii pivot = {s, n};
    pii ans = {s, n};
    while (l < r) {
        if (is_smaller(pii(s - a[l], n - 1), pivot)) {
            s -= a[l]; n --; l ++;
            if (is_smaller(pii(s, n), ans))
                ans = pii(s, n);
            continue;
        }
        s -= a[r]; n --; r --;
        if (is_smaller(pii(s, n), ans))
            ans = pii(s, n);
    }

    long double x = -ans.st * pivot.nd + ans.nd * pivot.st, y = pivot.nd * ans.nd;
    return x / y;
}

long double checkR(int l, int r, int n) {
    ll s = 0;
    rep(i, 1, n) s += a[i];
    pii pivot = {s, n};
    pii ans = {s, n};
    while (l < r) {
        if (is_smaller(pivot, pii(s - a[r], n - 1))) {
            s -= a[r]; n --; r --;
            if (is_smaller(ans, pii(s, n)))
                ans = pii(s, n);
            continue;
        }
        s -= a[l]; n --; l ++;
        if (is_smaller(ans, pii(s, n)))
            ans = pii(s, n);
    }
    long double x = ans.st * pivot.nd - ans.nd * pivot.st, y = pivot.nd * ans.nd;
    // << "R: " << x << ' ' << y << '\n';
    return x / y;
}

int main() {

    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    #ifndef ONLINE_JUDGE
       // freopen(file".inp", "r", stdin);
       // freopen(file".out", "w", stdout);
    #endif // ONLINE_JUDGE

    cin >> n;
    rep(i, 1, n)
        cin >> a[i];
    cout << setprecision(10) << fixed << min(checkL(1, n, n), checkR(1, n, n));

    return 0;
}

• Subtask 1: 0 / 1
• Subtask 2: 0 / 33
• Subtask 3: 0 / 33
• Subtask 4: 0 / 33