Submission #957367

#	Time	Username	Problem	Language	Result	Execution time	Memory
957367		_callmelucian	Sure Bet (CEOI17_sure)	C++14	100 / 100	605 ms	8440 KiB

sure

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

typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pl;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tt;

#define all(a) a.begin(), a.end()
#define filter(a) a.erase(unique(all(a)), a.end())

const int mn = 1e5 + 5;
const ld eps = 1e-9;
const ld M = 1e9;

ld a[mn], b[mn], pre_a[mn], pre_b[mn];
int n;

bool ok (ld lb) {
    // check if there exist an answer >= lb
    for (int k = 0; k <= 2 * n; k++) {
        if (pre_a[min(n, k)] < lb + k) continue;
        int best = min(n, k);
        for (int b = min(n, k); b >= 1; b /= 2) {
            while (best - b >= 0 && pre_a[best - b] >= lb + k) best -= b;
        }
        if (pre_b[min(n, k - best)] >= lb + k) return 1;
    }
    return 0;
}

ld bs (ld L, ld R) {
    if (abs(L - R) < eps) return L;
    ld mid = (L + R) / 2.0;
    if (ok(mid + eps)) return bs(mid + eps, R);
    return bs(L, mid);
}

bool compare (ld a, ld b) { return a > b; }

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i] >> b[i];
    sort(a + 1, a + 1 + n, compare);
    sort(b + 1, b + 1 + n, compare);

    for (int i = 1; i <= n; i++) {
        pre_a[i] = pre_a[i - 1] + a[i];
        pre_b[i] = pre_b[i - 1] + b[i];
    }

    cout << fixed << setprecision(4) << bs(0, M) << "\n";

    return 0;
}

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