Submission #660612

#	Time	Username	Problem	Language	Result	Execution time	Memory
660612		SansPapyrus683	Mobile (BOI12_mobile)	C++17	100 / 100	944 ms	35392 KiB

mobile

#include <iostream>
#include <iomanip>
#include <cmath>
#include <vector>
#include <algorithm>

using std::cout;
using std::endl;
using std::vector;
using Point = std::pair<long long, long long>;

constexpr int PRECISION = 4;

double dist(const Point& p1, const Point& p2) {
    long long dx = p1.first - p2.first;
    long long dy = p1.second - p2.second;
    return std::sqrt(dx * dx + dy * dy);
}

/**
 * https://oj.uz/problem/view/BOI12_mobile
 * 2 10
 * 0 0
 * 11 1 should output something close to 5.545455
 */
int main() {
    int tower_num;
    int road_len;
    std::cin >> tower_num >> road_len;

    vector<Point> towers(tower_num);
    for (Point& t : towers) {
        std::cin >> t.first >> t.second;
    }
    std::sort(towers.begin(), towers.end());

    long long div_by = std::pow(10, PRECISION);
    long long lo = 0;
    long long hi = INT64_MAX / 2;
    long long valid = -1;
    while (lo <= hi) {
        long long mid = (lo + hi) / 2;
        double power = (double) mid / div_by;

        double at = 0;
        for (Point& t : towers) {
            double sqrt = std::sqrt(power * power - t.second * t.second);
            double start = -sqrt + t.first;
            double end = sqrt + t.first;
            if (start <= at) {
                at = std::max(at, end);
            }
        }

        if (at >= road_len) {
            valid = mid;
            hi = mid - 1;
        } else {
            lo = mid + 1;
        }
    }

    cout << std::fixed << std::setprecision(PRECISION)
         << (double) valid / div_by << endl;
}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
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• Subtask 5: 4 / 4
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• Subtask 11: 5 / 5
• Subtask 12: 5 / 5
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• Subtask 17: 5 / 5
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• Subtask 20: 5 / 5
• Subtask 21: 5 / 5