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Submission #1083685

# Submission time Handle Problem Language Result Execution time Memory
1083685 2024-09-03T20:21:51 Z vjudge1 Mobile (BOI12_mobile) C++17
0 / 100
 590 ms 32404 KB 
#include <iostream>
#include <vector>
#include <cmath>
#include <iomanip>

using namespace std;

// Function to check if a given radius R can cover the entire highway
bool canCoverAllPoints(const vector<pair<double, double>>& stations, double R, double L) {
    double coveredUntil = 0.0;

    for (const auto& station : stations) {
        double xi = station.first;
        double yi = station.second;

        if (yi > R) continue; // This base station is too far away to help

        // Calculate the maximum x-range this station can cover
        double d = sqrt(R * R - yi * yi);
        double coverageStart = max(0.0, xi - d);
        double coverageEnd = xi + d;

        // Extend the coverage
        coveredUntil = max(coveredUntil, coverageEnd);

        if (coveredUntil >= L) return true; // Covered the entire highway
    }

    return coveredUntil >= L;
}

int main() {
    int N;
    double L;
    cin >> N >> L;

    vector<pair<double, double>> stations(N);
    for (int i = 0; i < N; ++i) {
        double xi, yi;
        cin >> xi >> yi;
        stations[i] = {xi, yi};
    }

    // Binary search for the smallest possible R
    double low = 0.0;
    double high = 1e9;
    double epsilon = 1e-4; // Precision to ensure accuracy within 1e-3

    while (high - low > epsilon) {
        double mid = (low + high) / 2.0;
        if (canCoverAllPoints(stations, mid, L)) {
            high = mid; // Try smaller radius
        } else {
            low = mid; // Increase radius
        }
    }

    cout << fixed << setprecision(6) << high << endl;
    return 0;
}

Compilation message

mobile.cpp: In function 'bool canCoverAllPoints(const std::vector<std::pair<double, double> >&, double, double)':
mobile.cpp:20:16: warning: unused variable 'coverageStart' [-Wunused-variable]
   20 |         double coverageStart = max(0.0, xi - d);
      |                ^~~~~~~~~~~~~

Subtask #1
0 / 4.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 348 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #2
0 / 4.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 348 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #3
0 / 4.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 348 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 4.0

# Verdict Execution time Memory Grader output
1 Incorrect 3 ms 348 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #5
0 / 4.0

# Verdict Execution time Memory Grader output
1 Incorrect 3 ms 344 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #6
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 3 ms 348 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #7
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 37 ms 2392 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #8
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 41 ms 2160 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #9
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 45 ms 2388 KB Output is correct
2 Incorrect 43 ms 2648 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #10
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 64 ms 3380 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #11
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 60 ms 3408 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #12
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 253 ms 12368 KB Output is correct
2 Incorrect 300 ms 15908 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #13
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 300 ms 16208 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #14
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 311 ms 14928 KB Output is correct
2 Incorrect 341 ms 19028 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #15
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 370 ms 19524 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #16
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 358 ms 17256 KB Output is correct
2 Incorrect 396 ms 22100 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #17
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 416 ms 22884 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #18
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 414 ms 19792 KB Output is correct
2 Incorrect 466 ms 25168 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #19
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 469 ms 25940 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #20
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 522 ms 24660 KB Output is correct
2 Incorrect 586 ms 31548 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #21
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 590 ms 32404 KB Output isn't correct
2 Halted 0 ms 0 KB -