Submission #639190

#	Time	Username	Problem	Language	Result	Execution time	Memory
639190		Pietra	Mobile (BOI12_mobile)	C++14	70 / 100	1095 ms	15980 KiB

mobile

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

const int maxn = 1e6 + 5 ;
const double inf = 2e9 ;

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

bool check(double r){

    double f = 0 ;

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

    return (f >= l) ;

}

int32_t main(){

    cin >> n >> l ; 

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

    double ini = 0, fim = inf, mid ;
    int it = 45 ;

    while(it--){
        mid = (ini + fim)/2 ;
       // printf("%.3lf\n", mid) ;
        if(check(mid)) fim = mid ;
        else ini = mid ;
    }

    cout << fixed << setprecision(3) << fim << "\n" ;
    //printf("%.3lf\n", best) ;

}

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