Submission #941386

#	Time	Username	Problem	Language	Result	Execution time	Memory
941386		Kavelmydex	Mobile (BOI12_mobile)	C++17	65 / 100	686 ms	18920 KiB

mobile

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pi pair<int,int>
#define vi vector<int>
#define rep(i,x,n) for(int i=x; i<n; ++i)
#define For(i,n) rep(i,0,n)
#define pb push_back
#define endl "\n"
#define sp ' '
#define f first
#define s second
#define sz size()
#define all(x) (x).begin(),(x).end()

const int N = 3e5+10, OO = 1e18, mod = 1e9+7;
void tr(int a, int b){cout << a << sp << b << endl;}
void cmx(int &a, int b){a = max(a,b);}
void cmn(int &a, int b){a = min(a,b);}

vector <pi> v;
int n,L;
bool ok(double m){
    double mn = 2e9, mx = -2e9, z = 0;
    For(i,n){
        auto [x,y] = v[i];
        if(y*y > m*m) continue;
        double d = sqrt(m * m - y * y);
        if(x-d <= z && z <= x+d){
            z = x+d;
        }   
        if(x-d < mn) mn = x-d;
        if(mx < x+d) mx = x+d;    
        if(mn <= 0 && L <= mx && z >= L) return 1;
    }
    return 0;
}
int32_t main() {
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n >> L;
    For(i,n){
        int x,y; cin >> x >> y;
        v.pb({x,y});
    }
    double l = 0, r = 1e10;
    For(i,60){
        double m = (l+r)/2;
        bool b1 = ok(m), b2 = ok(m);
        assert(b1 == b2);
        if(b1) r = m;
        else l = m;
    }
    cout << setprecision(10) << r << endl;
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
• Subtask 8: 5 / 5
• Subtask 9: 5 / 5
• Subtask 10: 0 / 5
• Subtask 11: 5 / 5
• Subtask 12: 0 / 5
• Subtask 13: 5 / 5
• Subtask 14: 0 / 5
• Subtask 15: 0 / 5
• Subtask 16: 0 / 5
• Subtask 17: 5 / 5
• Subtask 18: 0 / 5
• Subtask 19: 5 / 5
• Subtask 20: 0 / 5
• Subtask 21: 5 / 5