Submission #82076

#	Time	Username	Problem	Language	Result	Execution time	Memory
82076		FutymyClone	Mobile (BOI12_mobile)	C++14	50 / 100	1088 ms	73952 KiB

mobile

#include <bits/stdc++.h>

using namespace std;

const int N = 1e6 + 5;
const double eps = 1e-4;

struct Point {
    int x, y;
} a[N];

int n, m;

bool check (double mid) {
    vector <pair <double, double> > vec;
    for (int i = 1; i <= n; i++) {
        //(a[i].x - x)^2 + a[i].y^2 = mid^2
        double cur = mid * mid - 1LL * a[i].y * a[i].y;
        if (cur < 0) continue;
        double lx = -sqrt(cur) + a[i].x;
        double rx = sqrt(cur) + a[i].x;

        if (lx > m || rx < 0) continue;
        lx = max(lx, (double)0);
        rx = min(rx, (double)m);
        vec.push_back({lx, rx});
    }

    sort(vec.begin(), vec.end());
    double pt = 0;
    for (int i = 0; i < vec.size(); i++) {
        if (vec[i].first > pt) return false;
        pt = max(pt, vec[i].second);
    }

    if (pt < m) return false;
    return true;
}

int main(){
    scanf("%d %d", &n, &m);
    for (int i = 1; i <= n; i++) scanf("%d %d", &a[i].x, &a[i].y);

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

    cout << fixed << setprecision(10) << l;
    return 0;
}

Compilation message (stderr)

mobile.cpp: In function 'bool check(double)':
mobile.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < vec.size(); i++) {
                     ~~^~~~~~~~~~~~
mobile.cpp: In function 'int main()':
mobile.cpp:41:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~~
mobile.cpp:42:39: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for (int i = 1; i <= n; i++) scanf("%d %d", &a[i].x, &a[i].y);
                                  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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