Submission #906157

#	Time	Username	Problem	Language	Result	Execution time	Memory
906157		Ludissey	Mobile (BOI12_mobile)	C++14	0 / 100	511 ms	18892 KiB

mobile

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

signed main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int n,L; cin >> n >> L;
    vector<pair<double,double>> a;
    int N=0;
    for (int i = 0; i < n; i++){
        int x,y; cin >> x >> y;
        y=abs(y);
        if(i>0&&a[N-1].first==x) a[N-1].second=min(a[N-1].second,y);
        else{
            N++;    
            a.push_back({x,y});
        }
    }
    int l=0,r=1e9;
    while(r-l>0.0003){
        int mid=(l+r)/2;
        int rght=0;
        for (int i = 0; i < N; i++)
        {
            if(mid<a[i].second) continue;
            int pnt1=sqrt((mid*mid)-(a[i].second*a[i].second));
            if(a[i].first-pnt1<=rght) rght=max(rght, pnt1+a[i].second);
        }
        if(rght>=L) {
            r=mid;
        }else{
            l=mid;
        }
    }
    cout << setprecision(5) << fixed << (double)l << "\n";
    return 0;
}

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