Submission #1031428

#	Time	Username	Problem	Language	Result	Execution time	Memory
1031428		shezitt	Mobile (BOI12_mobile)	C++14	100 / 100	416 ms	15964 KiB

mobile

#include <bits/stdc++.h>

using namespace std;

using ll = long long;

#define int ll
#define vi vector<int>
#define ii pair<int,int>
#define x first
#define y second
#define fore(a, b, c) for(int a=b; a<c; ++a)
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define endl '\n'
#define dbg(x) cerr << #x << ": " << x << endl
#define raya cerr << "================" << endl;

double eps = 1e-4;

signed main(){

    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n, len;
    cin >> n >> len;

    vector<ii> p(n);
    fore(i, 0, n){
        cin >> p[i].x >> p[i].y;
    }

    double low = 0, high = 1e9+5;

    while((high - low) > eps){
        double mid = low + (high - low) / 2;
        
        double mx = 0;

        fore(i, 0, n){
            // double delta = (2*p[i].x)*(2*p[i].x)-4*(p[i].x*p[i].x+p[i].y*p[i].y-mid*mid);
            // double a = (2*p[i].x - sqrt(delta)) / 2;
            // double b = (2*p[i].x + sqrt(delta)) / 2;

            // simplificando:
            double delta = mid * mid - p[i].y * p[i].y;
            double a = p[i].x - sqrt(delta);
            double b = p[i].x + sqrt(delta);
            
            if(a <= mx){
                mx = max(mx, b);
            }
        }

        if(mx >= len){
            high = mid;
        } else {
            low = mid;
        }

    }

    cout << fixed << setprecision(6) << high;

}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
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• Subtask 12: 5 / 5
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• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
• Subtask 17: 5 / 5
• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5
• Subtask 21: 5 / 5