Submission #1254780

#	Time	Username	Problem	Language	Result	Execution time	Memory
1254780		zhaoxw	Mobile (BOI12_mobile)	C++20	100 / 100	764 ms	16072 KiB

mobile

#include<bits/stdc++.h>
using namespace std;
pair<long long,long long> p[1000005];
long long n,len;
bool check(double x)
{
    double l = 1,r = 0;
    for(int i = 1;i <= n;i++)
    {
        double d = sqrt(x*x-p[i].second*p[i].second);
        double a = p[i].first-d,b = p[i].first+d;
        if(a <= r) r = max(r,b),l = min(l,a);
    }
    if(l <= 0 && r >= len) return true;
    else return false;
}
int main()
{
    cin >> n >> len;
    for(int i = 1;i <= n;i++)
        cin >> p[i].first >> p[i].second;
    double maxn = 2e9,minn = 1e-4,ans = maxn;
    for(double d = maxn;d >= minn;d /= 2)
        while(ans-d >= 0 && check(ans-d)) ans -= d;
    cout << fixed << setprecision(4) << ans << '\n';
    return 0;
}

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• Subtask 21: 5 / 5