Submission #1240609

#	Time	Username	Problem	Language	Result	Execution time	Memory
1240609		Zero	Mobile (BOI12_mobile)	C++20	0 / 100	585 ms	16056 KiB

mobile

#include <bits/stdc++.h>
#define f first
#define ss second
using namespace std;

bool ok(double m, vector<pair<int,int>> a, int x){
    int n = a.size();
    for(int i=1; i < n; i ++){
        //if(a[i-1].f >= x && a[i].f >= x) break;
        double xo = a[i].f-sqrt(m*m-a[i].ss*a[i].ss), xo2 = a[i].f+sqrt(m*m-a[i].ss*a[i].ss);
        double d = (a[i-1].f-xo) * (a[i-1].f-xo) + a[i-1].ss*a[i-1].ss;
        double df = (a[i-1].f-xo2) * (a[i-1].f-xo2) + a[i-1].ss*a[i-1].ss;
        if(d > m*m && df > m*m) return 0;
        // double ds = (a[i].f - (m+a[i-1].f)) * (a[i].f-(m+a[i-1].f)) + (a[i].ss)*(a[i].ss);
        // ds = sqrt(ds);
        // if(ds>m*2) return 0;
    }
    return 1;
}

signed main(){
    cin.tie(0)->sync_with_stdio(0);
    int n,x; cin >> n >> x;
    vector<pair<int,int>> a(n);
    for(auto &i : a) cin >> i.first >> i.second;
    
    double l = 0, r = INT_MAX;
    for(int i=0; i < 100; i ++){
        double m = (l + r) / 2;
        if(ok(m,a,x)) r = m;
        else l=m;
    }
    cout << fixed << setprecision(6) << r;
}

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