praveenksingh / salesforce

To share with friends

SALESFORCE PROGRAMMING TEST

Congratulations. You are a strong candidate and we would like to see what you can do. You have two hours rs from the time you receive th this test to complete and return it, based on emailtime stamps.

This challenge contains a problem description and some requirements for the implementation. Please read the description and requirements carefully. Here’s how your solution will be evaluated, ed, in priority order (1 is highest priority) priority):

1. Does the program have your name included in a comment?
2. Does the program compile and execute according to the problem description?
3. Does the program exhibit good design techniques?
4. Do you use data structures and algorithms that would allow your program to work under high volume – that is, is your code scalable?
5. Is your code well formatted and easy to read? Do you have sufficient comments? Can the reviewer quickly determine how your program is organized and what you are trying to accomplish by each class / method?
6. Have you thoroughly tested all possible input combinations? Please write your code in Python, Ruby, Perl, BASH, C/C++, or Java. Thanks and good luck!

Problem Description: Package Installation and System Dependencies Dependencies between software packages are common in any Unix/Linux system. This means that to install a given software package package, another package must be installed beforehand. Additionally lower level software components are often required by multiple upper level packages. For example, both the telnet client program and the ftp client program require that the TCP/IP networking package.. Conversely, the TCP/IP p package ackage cannot be removed until all packages that depend on it (telnet telnet, ftp) are removed. We want you to design and write a program to automate the process of adding and removing software packages. To do this you will need to:

1 Salesforce.com

1. Maintain a record of installed packages and their dependencies. 2. Support explicitly installing a package in response to a command (unless it is already installed). 3. Support implicitly installing a package if it is needed to install another package. 4. Support explicitly removing a package in response to a command (if it is not needed to support other packages). 5. Support implicitly removing a package if it is no longer needed to support another component.

Requirements • •

Before installing a package, automatically install all the packages it requires. Before removing a package, confirm that no other packages require it. Dependent packages must be removed manually before the package can be removed.

Input The input received by your program will contain a sequence of commands, each on a separate line, containing no more than eighty characters. The command names (DEPEND, INSTALL, REMOVE, and LIST) always appear in uppercase starting in column one and the command line separator is one or more spaces. All appropriate DEPEND commands will appear before the occurrence of any INSTALL dependencies. The end of the input is marked by a line containing only the word END. Command Syntax: DEPEND item1 item2 [item3]

Package item1 depends on package item2 (and item3 or any additional packages).

INSTALL item1

Installs item1 and any other packages required by item1.

REMOVE item1

Removes item1 and, if possible, packages required by item1.

LIST

Lists the names of all currently installed packages.

END

Marks the end of input, when used in a line by itself.

2 Salesforce.com

Output

1. Echo each line of input.
2. Follow each echoed INSTALL or REMOVE line with the actions taken in response, making certain that the actions are given in the proper order.
3. For the LIST command, display the names of the components currently installed.
4. For the DEPEND and END commands, no output, except the echo, is produced.
5. For the DEPEND command, there will only be one dependency list per item. Sample Input DEPEND TELNET TCPIP NETCARD DEPEND TCPIP NETCARD DEPEND DNS TCPIP NETCARD DEPEND BROWSER TCPIP HTML INSTALL NETCARD INSTALL TELNET INSTALL foo REMOVE NETCARD INSTALL BROWSER INSTALL DNS LIST REMOVE TELNET REMOVE NETCARD REMOVE DNS REMOVE NETCARD INSTALL NETCARD REMOVE TCPIP REMOVE BROWSER REMOVE TCPIP LIST END Expected Sample Output DEPEND TELNET TCPIP NETCARD DEPEND TCPIP NETCARD DEPEND DNS TCPIP NETCARD DEPEND BROWSER TCPIP HTML INSTALL NETCARD NETCARD successfully installed INSTALL TELNET TCPIP successfully installed TELNET successfully installed INSTALL foo foo successfully installed REMOVE NETCARD

3 Salesforce.com

NETCARD is still needed. INSTALL BROWSER HTML successfully installed BROWSER successfully installed INSTALL DNS DNS successfully installed LIST HTML BROWSER DNS NETCARD foo TCPIP TELNET REMOVE TELNET TELNET successfully removed REMOVE NETCARD NETCARD is still needed REMOVE DNS DNS successfully removed REMOVE NETCARD NETCARD is still needed INSTALL NETCARD NETCARD is already installed REMOVE TCPIP TCPIP is still needed REMOVE BROWSER BROWSER successfully removed HTML is no longer needed HTML successfully removed TCPIP is no longer needed TCPIP successfully removed REMOVE TCPIP TCPIP is not installed LIST NETCARD foo END

4 Salesforce.com