Submission #1287695

#	Time	Username	Problem	Language	Result	Execution time	Memory
1287695		xyxwong	Mobile (BOI12_mobile)	C++20	8 / 100	438 ms	31652 KiB

mobile

#include<bits/stdc++.h>
#include<vector>
#include<algorithm>
#include<cmath>
using namespace std;
#define ll long long
#define ld long double
#define fi first 
#define se second 
#define flt float
#define pld pair<ld,ld>

int main(){
    ios::sync_with_stdio(0);
    cin.tie(nullptr);
    ll n;ld l;cin>>n>>l;
    vector<pld>v(n);
    for(auto&p:v)cin>>p.fi>>p.se;
    ld lo = 0,hi = 1.0*2e9;
    ld ans = 0;
    while(hi-lo>1e-6){
        ld r = (lo+hi)/2;
        ld a=1e-12;
        for(ll i = 0;i<n;i++){
            auto&p = v[i];
            if(p.se*p.se>r*r)continue;
            ld tmp = sqrtl(r*r-p.se*p.se);
            ld bx = p.fi - tmp,ex = p.fi + tmp;
            if(bx<=a)a = max(a,ex);
        }
        if(a>=l){
            hi = r;
            ans - r;
        }else{
            lo = r;
        }
    }
    cout.precision(6);
    cout<<hi;
}

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