제출 #1063749

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1063749		daviedu	Mobile (BOI12_mobile)	C++17	100 / 100	961 ms	46488 KiB

mobile

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

#define fastio ios_base::sync_with_stdio(0); cin.tie(0)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ll long long
#define ld long double

struct P{
    ll x, y;
};

void dbg_out() { cerr << endl; }
template <typename H, typename... T>
void dbg_out(H h, T... t) { cerr << ' ' << h; dbg_out(t...); }
#define dbg(...) { cerr << #__VA_ARGS__ << ':'; dbg_out(__VA_ARGS__); }

const ld prec = 0.0005;
const ld MX = 2e9;
vector<pair<ld, ld>> points;
int n, len;

bool f(ld r){
    ld right=0;
    for (auto& [x, y]: points){
        if (r < y) continue;
        ld dx = sqrtl(r*r - y*y);
        if (x-dx <= right) right = max(right, x+dx);
    }
    return right >= len;
}

signed main(){
    fastio;
    cin >> n >> len;
    points.resize(n);
    for (int i=0; i<n; i++){
        cin >> points[i].first;
        cin >> points[i].second;
    }
    
    ld l=0, r=MX, ans=MX;
    while (r-l >= prec){
        ld m = (l+r)/2;
        if (f(m)) r = m, ans = m;
        else l = m;
    }
    cout << fixed << setprecision(13);
    cout << ans << '\n';
}

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