Submission #1330361

#	Time	Username	Problem	Language	Result	Execution time	Memory
1330361		randi_pav	Mobile (BOI12_mobile)	C++20	4 / 100	1097 ms	65312 KiB

mobile

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

bool check(long double R, int n, int l, vector<pair<long long, long long>>& towers) {
    vector<pair<long double, long double>> segments;
    for (int i = 0; i < n; i++) {
        if (R >= towers[i].second) {
            long double d = sqrtl(R * R - (long double)towers[i].second * towers[i].second);
            segments.push_back({(long double)towers[i].first - d, (long double)towers[i].first + d});
        }
    }
    if (segments.empty()) return false;
    sort(segments.begin(), segments.end());
    
    long double current_reach = 0;
    if (segments[0].first > 0) return false;
    
    for (auto& seg : segments) {
        if (seg.first <= current_reach) {
            current_reach = max(current_reach, seg.second);
        }
    }
    return current_reach >= (long double)l;
}

int main() {
    int n, l;
    cin >> n >> l;
    vector<pair<long long, long long>> towers(n);
    for (int i = 0; i < n; i++) cin >> towers[i].first >> towers[i].second;

    long double low = 0, high = 2e9; // L aur coordinates ke hisaab se max possible distance
    for (int i = 0; i < 100; i++) { // 100 iterations for high precision
        long double mid = (low + high) / 2.0;
        if (check(mid, n, l, towers)) high = mid;
        else low = mid;
    }

    cout << fixed << setprecision(3) << high << endl;
    return 0;
}

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