Submission #906178

#	Time	Username	Problem	Language	Result	Execution time	Memory
906178		Ludissey	Mobile (BOI12_mobile)	C++14	100 / 100	312 ms	10788 KiB

mobile

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

double dist(double x1, double y1, double x2, double y2){
    double dist=sqrt(pow((x1-x2),2)+pow((y1-y2),2));
    return dist;
}

signed main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int N,L; cin >> N >> L;
    vector<pair<int,int>> a;
    double toO=1e9,toL=1e9;
    for (int i = 0; i < N; i++){
        int x,y; cin >> x >> y;
        y=abs(y);
        if(i>0&&a[a.size()-1].first==x) a[a.size()-1].second=min(a[a.size()-1].second,y);
        else{
            a.push_back({x,y});
        }
        toO=min(dist(0,0,x,y),toO);
        toL=min(dist(L,0,x,y),toL);
    }
    N=a.size();
    double l=max(toO,toL),r=1e9;
    while(r-l>0.0009){
        double mid=(l+r)/2;
        double rght=0;
        for (int i = 0; i <N; i++)
        {
            if(mid<(double)a[i].second) continue;
            double pnt1=a[i].first-sqrt(pow(mid,2)-pow((double)a[i].second,2)),pnt2=(double)a[i].first+sqrt(pow(mid,2)-pow((double)a[i].second,2));
            if(pnt1<=rght) rght=max(rght, pnt2);
        }
        if(rght>=L) {
            r=mid;
        }else{
            l=mid;
        }
    }
    cout << setprecision(3) << fixed << l << "\n";
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
• Subtask 8: 5 / 5
• Subtask 9: 5 / 5
• Subtask 10: 5 / 5
• Subtask 11: 5 / 5
• Subtask 12: 5 / 5
• Subtask 13: 5 / 5
• Subtask 14: 5 / 5
• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
• Subtask 17: 5 / 5
• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5
• Subtask 21: 5 / 5