Submission #973109

#	Time	Username	Problem	Language	Result	Execution time	Memory
973109		njoop	Mobile (BOI12_mobile)	C++17	0 / 100	1067 ms	49512 KiB

mobile

#include <bits/stdc++.h>
#define pi pair<double, double>
using namespace std;

double x, y, L, l=0, r=1e9, mid, de, cov;
pi arr[1000010];
vector<pi> in;
int n;

bool solve(double rad) {
    in.clear();
    cov = 0;
    for(int i=1; i<=n; i++) {
        de = pow(rad, 2) - pow(abs(arr[i].second), 2);
        de = sqrt(de);
        if(de < 0) continue;
        in.push_back({arr[i].first-de, arr[i].first+de});
    }
    sort(in.begin(), in.end());
    for(auto i: in) {
        if(i.first > cov) return 0;
        cov = max(cov, i.second);
        if(cov >= L) return 1;
    }
    return 0;
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> L;
    for(int i=1; i<=n; i++) {
        cin >> arr[i].first >> arr[i].second;
    }
    while(l+0.00001 < r) {
        mid = (l+r)/2;
        if(solve(mid)) {
            r = mid;
        } else {
            l = mid + 0.00001;
        }
    }
    cout << fixed << setprecision(6) << l;
    return 0;
}

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