Submission #1194607

#	Time	Username	Problem	Language	Result	Execution time	Memory
1194607		cpismylifeOwO	Mobile (BOI12_mobile)	C++20	32 / 100	1097 ms	69304 KiB

mobile

#include <bits/stdc++.h>

using namespace std;

const long long mod = 1e9 + 7;
const int MaxN = 1e6 + 5;

int n;
long long l;
pair<long long, long long> arr[MaxN];

void Inp()
{
    cin >> n >> l;
    for (int x = 1; x <= n; x++)
    {
        cin >> arr[x].first >> arr[x].second;
    }
}

bool Check(long double k)
{
    vector<long double> in, out;
    int cur = 0;
    for (int x = 1; x <= n; x++)
    {
        if (abs(arr[x].second) >= k)
        {
            cur++;
            continue;
        }
        long double p = sqrtl(k * k - arr[x].second * arr[x].second);
        if (arr[x].first - p >= 0)
        {
            in.push_back(0);
            out.push_back((long double)arr[x].first - p);
        }
        if (arr[x].first + p <= l)
        {
            in.push_back((long double)arr[x].first + p);
            out.push_back(l);
        }
    }
    sort(in.begin(), in.end());
    sort(out.begin(), out.end());
    reverse(in.begin(), in.end());
    reverse(out.begin(), out.end());
    while (!in.empty() || !out.empty())
    {
        long double p = 0;
        if (out.empty() || (!in.empty() && in.back() < out.back()))
        {
            p = in.back();
        }
        else
        {
            p = out.back();
        }
        while (!in.empty() && in.back() == p)
        {
            cur++;
            in.pop_back();
        }
        if (cur == n)
        {
            return true;
        }
        while (!out.empty() && out.back() == p)
        {
            cur--;
            out.pop_back();
        }
    }
    return false;
}

void Exc()
{
    long long l = 0, r = 1e18, mid, res = 0;
    while (l <= r)
    {
        mid = (l + r) / 2;
        if (Check((long double)((long double)mid / 100000.0)))
        {
            res = mid;
            l = mid + 1;
        }
        else
        {
            r = mid - 1;
        }
    }
    cout << fixed << setprecision(5) << (long double)((long double)res / 100000.0);
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int test = 1;
    //cin >> test;
    for (int x = 1; x <= test; x++)
    {
        Inp();
        Exc();
    }
    return 0;
}

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