Submission #1332366

#	Time	Username	Problem	Language	Result	Execution time	Memory
1332366		ug12	Mobile (BOI12_mobile)	C++20	100 / 100	359 ms	16084 KiB

mobile

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int ll
using pii = pair<double, double>;
#define x first
#define y second

const int N = 1e6 + 5, M = 1e6 + 5;
const double eps = 1e-4;
int n, len;
vector<pii> a(N);

bool check(double mid){
    
    double r = 0.0;
    for(int i = 1;i <= n;i++){
        double h = abs(a[i].y);
        if(h >= mid) continue;
        double dist = sqrt(mid * mid - h * h);
        double start = a[i].x - dist;
        double end = a[i].x + dist;
        if(start <= r) r = max(r, end);
    }
    return r >= len;

}

void solve(){

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

    double l = 0, r = 2e9, mid;
    while(r - l >= eps){
        mid = (l + r) / 2;
        if(check(mid)) r = mid - eps;
        else l = mid + eps;
    }

    cout << fixed << setprecision(12) << r + eps;

}
 
signed main(){
    ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);

    solve();
 
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
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• Subtask 20: 5 / 5
• Subtask 21: 5 / 5