Language: PHP

Description: Write a function that provides a change directory (cd) function for an abstract file system. Notes: root path is '/'. path separator is '/'. parent directory is addressable as '..'. directory names consist only of English alphabet letters (A-Z and a-z). the function will not be passed any invalid paths. do not use built-in path-related functions.

For example: $path = new Path('/a/b/c/d'); $path->cd('../x'); echo $path->currentPath; should display '/a/b/c/x'.

How To Submit: Complete the source file named change_directory.php.

Language: Python/PHP

Description: Suppose you have: a haversine(lat1, lng1, lat2, lng2) function that returns the distance (measured in km) between the coordinates of two given geographic point (lat and lng are latitude and longitude)

an array of geographical zones (locations): locations = [ {'id': 1000, 'zip_code': '37069', 'lat': 45.35, 'lng': 10.84}, {'id': 1001, 'zip_code': '37121', 'lat': 45.44, 'lng': 10.99}, {'id': 1001, 'zip_code': '37129', 'lat': 45.44, 'lng': 11.00}, {'id': 1001, 'zip_code': '37133', 'lat': 45.43, 'lng': 11.02}, ... ];

an array of shoppers: shoppers = [ {'id': 'S1', 'lat': 45.46, 'lng': 11.03, 'enabled': true}, {'id': 'S2', 'lat': 45.46, 'lng': 10.12, 'enabled': true}, {'id': 'S3', 'lat': 45.34, 'lng': 10.81, 'enabled': true}, {'id': 'S4', 'lat': 45.76, 'lng': 10.57, 'enabled': true}, {'id': 'S5', 'lat': 45.34, 'lng': 10.63, 'enabled': true}, {'id': 'S6', 'lat': 45.42, 'lng': 10.81, 'enabled': true}, {'id': 'S7', 'lat': 45.34, 'lng': 10.94, 'enabled': true}, ];

The goal is to calculate the percentage of the zone covered by enabled shoppers (coverage). One shopper covers a zone if the distance among the coordinates is less than 10 km. Resulted array should be sorted (desc) as the following one:

sorted = [ {shopper_id': 'S3', 'coverage': 72}, {shopper_id': 'S1', 'coverage': 43}, {shopper_id': 'S6', 'coverage': 12}, ];

How to submit: Complete the source code file named haversine_coverage.py|php.