Submission #1136458

#	Time	Username	Problem	Language	Result	Execution time	Memory
1136458		concua	Mobile (BOI12_mobile)	C++20	0 / 100	640 ms	16068 KiB

mobile

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

const int N = 1e6 + 1;
pair<double, double> p[N];

int n, L;

double pre = 0.0;

bool check(double x) {
    pre = 0.0; 
    for (int i = 1; i <= n; i++){
        if (x * x < p[i].second * p[i].second){
            return false; 
        }
        
        double delta = sqrt(x * x - p[i].second * p[i].second);

        if (pre > p[i].first - delta){
            
            pre = max(pre, p[i].first + delta);
        } 
        else{
            
            pre = p[i].first - delta;
        }
    }

    return pre >= L;
}

int main() {
    cin >> n >> L;
    for (int i = 1; i <= n; i++) {
        cin >> p[i].first >> p[i].second;
    }

    double l = 0, r = 1e9 + 1;

    while (r - l > 1e-3){
        double mid = (r + l) / 2;

        if (check(mid)){
            
            r = mid;
            
        } 
        else{
            
            l = mid;
            
        }
    }

    cout << fixed << setprecision(4) << r << "\n";

    return 0;
}

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