defibrillators

Defibrillators

Problem Description

The city of Montpellier has equipped its streets with defibrillators, and the data corresponding to their positions is available. The task is to write a program that helps users find the nearest defibrillator to their current location.

Inputs

1. User Location:

   • Line 1: User's longitude (in degrees, comma-separated).
   • Line 2: User's latitude (in degrees, comma-separated).
   • Line 3: The number N of defibrillators in the city.

2. Defibrillators Data: Each of the next N lines contains the following fields separated by semicolons (;):

   • A number identifying the defibrillator.
   • Name of the defibrillator.
   • Address.
   • Contact Phone number.
   • Longitude (degrees, comma-separated).
   • Latitude (degrees, comma-separated).

Output

The program should display the name of the defibrillator that is closest to the user’s current position.

Distance Formula

The distance d between the user and a defibrillator is calculated as:

x = (longitudeB - longitudeA) * cos((latitudeA + latitudeB) / 2)
y = latitudeB - latitudeA
distance = hypot(x, y) * 6371

Constraints

• 0 < N < 10,000

Example

Input

3,879483
43,608177
3
1;Maison de la Prevention Sante;6 rue Maguelone 340000 Montpellier;;3,87952263361082;43,6071285339217
2;Hotel de Ville;1 place Georges Freche 34267 Montpellier;;3,89652239197876;43,5987299452849
3;Zoo de Lunaret;50 avenue Agropolis 34090 Mtp;;3,87388031141133;43,6395872778854

Output

Maison de la Prevention Sante

Code Example

function toRadians(degrees) {
    return degrees * Math.PI / 180;
}

// Parse the user's longitude and latitude
const LON = parseFloat(readline().replace(',', '.'));
const LAT = parseFloat(readline().replace(',', '.'));

// Number of defibrillators
const N = parseInt(readline());

let closestDefibName = '';
let closestDistance = Infinity;

// Loop over each defibrillator to calculate the distance
for (let i = 0; i < N; i++) {
    const DEFIB = readline().split(';');
    const defibLon = parseFloat(DEFIB[4].replace(',', '.'));
    const defibLat = parseFloat(DEFIB[5].replace(',', '.'));

    // Calculate the distance using the provided formula
    const x = (defibLon - LON) * Math.cos(toRadians((LAT + defibLat) / 2));
    const y = defibLat - LAT;
    const distance = Math.hypot(x, y) * 6371;  // Earth's radius in kilometers

    // Check if this defibrillator is closer than the current closest
    if (distance < closestDistance) {
        closestDistance = distance;
        closestDefibName = DEFIB[1];
    }
}

// Output the name of the closest defibrillator
console.log(closestDefibName);