# Lyft Programming Challenge

The Lyft programming challenge is an optional part of the job application to be a Software Engineer at Lyft.

This is copy pasted from the job posting:

Calculate the detour distance between two different rides. Given four latitude / longitude pairs, where driver one is traveling from point A to point B and driver two is traveling from point C to point D, write a function (in your language of choice) to calculate the shorter of the detour distances the drivers would need to take to pick-up and drop-off the other driver.

Broken down we have:

• There are two different trips
• Consisting of four points (A to B and C to D)
• Calculate which one is shorter ACDB or CABD

Using the Haversine formula, we can obtain the distance of the trip or from two different points in a plot.

JavaScript

``````// Config should be taken from an input
var metric = true;
var Radius; // Radius of the Earth
if (metric === true) {
Radius = 6371; // in km
} else {
Radius = 3963.1676; // in miles
}

/*
*  Converts a number into radians
*/
return num*Math.PI/180;
}

/*
*  Object point in a sphere
*/
function point(lat, lon) {
this.lat = lat;
this.lon = lon;
}

/*
*  Calculate the distance between two points
*/
function calcDistance(X, Y) {
var xLat = toRadians(X.lat);
var yLat = toRadians(Y.lat);
var diffLat = toRadians(xLat - yLat);
var diffLon = toRadians(X.lon - Y.lon);

// Haversine Formula
var a = Math.pow(Math.sin(diffLat/2), 2) + (Math.cos(xLat) * Math.cos(yLat) * Math.pow(Math.sin(diffLon/2), 2));
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = Radius * c;

return d;
}

function test(){
var A = new point(1, 1);
var B = new point(2, 3);
var C = new point(5, 8);
var D = new point(13, 21);

// Since it is a rectangle we need only calculate two trips
var distAB = calcDistance(A, B);
var distCD = calcDistance(C, D);

if (distAB > distCD) {
console.log("ACDB is the shorter path!");
} else if (distAB == distCD) {
console.log("Either driver can do it!")
} else {
console.log("CABD is the shorter path!");
}
}``````

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