Submission #465871

#	Time	Username	Problem	Language	Result	Execution time	Memory
465871		joshualiu555	Mobile (BOI12_mobile)	C++14	0 / 100	1094 ms	48240 KiB

mobile

/*
  _____                                     _        _
 / ____|                                   | |      | |
| |  __ _ __ __ _ ___ ___ _   _ _ __   ___ | |_ __ _| |_ ___
| | |_ | '__/ _` / __/ __| | | | '_ \ / _ \| __/ _` | __/ _ \
| |__| | | | (_| \__ \__ \ |_| | |_) | (_) | || (_| | || (_) |
 \_____|_|  \__,_|___/___/\__, | .__/ \___/ \__\__,_|\__\___/
                           __/ | |
                          |___/|_|
*/

#include <fstream>
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <numeric>
#include <array>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <cmath>
#include <cstring>
#include <bitset>
#include <string>
#include <sstream>

using namespace std;

using ll = long long;
const int INF = 1e6 + 5;
const int MOD = 1e9 + 7;
const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, 1, -1};

int N, L;
pair<ll, ll> xy[INF];

bool check (double radius) {
    vector<pair<double, double>> seg;
    for (int i = 0; i < N; i++) {
        double horz = sqrt(radius * radius - xy[i].second * xy[i].second);
        double left = xy[i].first - horz, right = xy[i].first + horz;
        seg.push_back(make_pair(left, right));
    }
    if (seg[0].first > 0) return false;
    for (int i = 1; i < N; i++) {
        if (seg[i].first <= seg[i - 1].second && seg[i].second >= seg[i - 1].second) {
            continue;
        } else {
            return false;
        }
    }
    if (seg[seg.size() - 1].second < L) return false;
    return true;
}

int main()
{
    std::ios_base::sync_with_stdio(false); cin.tie(0);

//    ifstream cin(".in");
//    ofstream cout(".out");

    cin >> N >> L;
    for (int i = 0; i < N; i++) cin >> xy[i].first >> xy[i].second;

    double l = 0, r = 1.5 * 1e9;
    for (int i = 0; i < 100; i++) {
        double m = (l + r) / 2;
        if (check(m)) {
            r = m;
        } else {
            l = m;
        }
    }

    cout << fixed << setprecision(6) << l << '\n';

    return 0;
}

/*
 *
*/

//

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