Submission #639202

#	Time	Username	Problem	Language	Result	Execution time	Memory
639202		Pietra	Mobile (BOI12_mobile)	C++14	80 / 100	1089 ms	16060 KiB

mobile

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

const int maxn = 2e6 + 5 ;
const int inf = 2e10 + 5 ;

double n, l, x[maxn], y[maxn] ;

bool check(double r){

    double f = 0 ;

    for(int i = 1 ; i <= n ; i++){
        double dx = sqrt((r*r) - (y[i]*y[i])) ;
        double ini = x[i] - dx, fim = x[i] + dx ;
        if(ini <= f + 1e-9) f = max(f, fim) ;
    }

    return (f + 1e-9 >= l) ;
}

int32_t main(){

    cin >> n >> l ;

    for(int i = 1 ; i <= n ; i++) cin >> x[i] >> y[i] ;

    double ini = 0, fim = inf*1.000, mid ;
    int ct = 45 ;

    while(ct--){
        mid = (ini + fim)/2 ;
        if(check(mid)) fim = mid ;
        else ini = mid ;
    }

    cout << fixed << setprecision(6) << fim << "\n" ;

}

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