Submission #732378

#	Time	Username	Problem	Language	Result	Execution time	Memory
732378		uy842003	Mobile (BOI12_mobile)	C++17	8 / 100	1079 ms	53792 KiB

mobile

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

const double eps = 1e-5;

bool cmp_less(double a, double b) {
    return a + eps < b;
}

bool cmp_less_equal(double a, double b) {
    return a < b + eps;
}

bool cmp_range(pair<double, double> &p1, pair<double, double> &p2) {
    return cmp_less(p1.first, p2.first);
}

bool inside(double l, double r, double m) {
    return cmp_less_equal(l, m) && cmp_less_equal(m, r);
}

int main() {

    int n, len;
    cin >> n >> len;
    vector<pair<int, int>> cor(n);
    for (int i = 0; i < n; i++)
        cin >> cor[i].first >> cor[i].second;
    double l = 0, r = 2e9 + 7, m;
    while (l < r) {
        m = (l + r) / 2;
        vector<pair<double, double>> range, real_range;
        for (int i = 0; i < n; i++) {
            if (cmp_less_equal(m, abs(cor[i].second))) continue;
            double dx = sqrt(m * m - cor[i].second * cor[i].second);
            range.push_back({cor[i].first - dx, cor[i].first + dx});
        }
        sort(range.begin(), range.end(), cmp_range);
        pair<double, double> cur_range = {-1, -1};
        if (range.size() > 0) cur_range = *range.begin();
        for (int i = 0; i < range.size(); i++) {
            if (inside(cur_range.first, cur_range.second, range[i].first) && cmp_less(cur_range.second, range[i].second))
                cur_range.second = range[i].second;
            if (!inside(cur_range.first, cur_range.second, range[i].first) || i + 1 == range.size()) {
                real_range.push_back(cur_range);
                cur_range = range[i];
            }
        }
        bool iok = false;
        for (int i = 0; i < real_range.size(); i++) {
            if (inside(real_range[i].first, real_range[i].second, 0) && inside(real_range[i].first, real_range[i].second, len)) {
                iok = true;
                break;
            }
        }
        if (iok)
            r = m;
        else
            l = m + eps;
    }
    cout << setprecision(4) << fixed;
    cout << r << endl;

    return 0;
}

Compilation message (stderr)

mobile.cpp: In function 'int main()':
mobile.cpp:41:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<double, double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |         for (int i = 0; i < range.size(); i++) {
      |                         ~~^~~~~~~~~~~~~~
mobile.cpp:44:85: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<double, double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |             if (!inside(cur_range.first, cur_range.second, range[i].first) || i + 1 == range.size()) {
      |                                                                               ~~~~~~^~~~~~~~~~~~~~~
mobile.cpp:50:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<double, double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   50 |         for (int i = 0; i < real_range.size(); i++) {
      |                         ~~^~~~~~~~~~~~~~~~~~~

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