Submission #999878

#	Time	Username	Problem	Language	Result	Execution time	Memory
999878		Whisper	Mobile (BOI12_mobile)	C++17	100 / 100	650 ms	25960 KiB

mobile

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define REPD(i, n) for (int i = (n) - 1; i >= 0; --i)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)


constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

/*
    Phu Trong from Nguyen Tat Thanh High School for gifted student
*/

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }

#define MAX     1000005
int numPoint;
double lim;
struct Point{
    double x, y;
    Point(){}
    Point(double _x, double _y): x(_x), y(_y){}
} A[MAX];

const double eps = 1e-5;

double dist(Point a, Point b){
    return (double)(sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y)));
}
signed main(){
    #define name "Whisper"
    cin.tie(nullptr) -> sync_with_stdio(false);
    //freopen(name".inp", "r", stdin);
    //freopen(name".out", "w", stdout);
    cin >> numPoint >> lim;
    for (int i = 1; i <= numPoint; ++i){
        cin >> A[i].x >> A[i].y;
    }
    double ans = 0.0;
    double l = 1, r = 1.5e9;

    auto check = [&](double dist) -> bool{
        double cur = 0;
        for (int i = 1; i <= numPoint; ++i){
            double l = A[i].x - sqrt(dist * dist - A[i].y * A[i].y);
            double r = A[i].x + sqrt(dist * dist - A[i].y * A[i].y);
            if (l <= cur) maximize(cur, r);
        }
        return cur >= lim;
    };

    while (r - l > eps){
        double m = (l + r) / 2;
        if(check(m)) r = m;
        else l = m;
    }
    cout << setprecision(5) << fixed << r;
}

Compilation message (stderr)

mobile.cpp: In function 'int main()':
mobile.cpp:62:12: warning: unused variable 'ans' [-Wunused-variable]
   62 |     double ans = 0.0;
      |            ^~~

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