Big Code – Good Code

Big Code, a Good Code? Sounds awkward? A Good code I mean here is a code which runs quicker than other solutions for the same problem.

if T(Sol1) < T(Sol2) Then, Solution 1 is a Good code., Where T is Time function , measures Time Taken

( though there are various other constraints involved, for time being let not discuss them )

Hardcore programmers are always tries to write short programs. They couple few lines of code into one and show that they have done a great coding.  But, things are not always the way it looks. Short is sweet, but not always !

Look into this code, 3 solutions for one simple problem.

Problem: Find the greatest of two numbers a, b

Million Dollar Question

Which code runs faster? If you have chosen the A’s code as faster. You have correctly made a wrong decision.

The fastest program is the B’s program. So, 3 lines of code, still fastest code? Ok.

In the A’s code,  consider if a < b, two operations should be performed.

• Compare ‘a’ , ‘b’
• Branch to Else if ‘a’ < ‘b’
• Return the expression ‘b’

But in B’s solution, we have already assigned a value to ‘x’. Only job is to compare and Assign. So the second operation is saved.

In such a small code, you won’t find a big difference. But think of a macro system with MLOC ( Million Lines of Code ).

I will explain you by solving a bit complex problem, come on join me.

Problem: Given number ‘N’ , split into ‘k’ integers, such that N = k1 + k2 + k3 +…kn and k1 * k2 * k3 is maximum.

You can try various solutions. One simple solution is

Great code, you would be proud to write one line solution of such great problem. But wait, is your code is faster to run for N > 10^10, K > 10^5?

Consider the optimize solution

More optimised

The last code works much faster than any other. Try looping it for million times with various values of ‘N & k ‘. and measure the time it takes to complete the million time execution.

How to write a speedy code?

So, this is yet another million dollar question. Take a look at the above three solutions. You will find a resemblance.

Solution – 1 is a generalized form of other two. Solution – 3 is more detailed form of Solution – 1.

So, what is been detailed in the Solution 3. If you look at more closely, you will find that Solution-3 has checks for ‘Boundary Conditions’.

Boundary Conditions are very important scenarios in any Logical System. You prove that system works perfect for boundary conditions, you prove the system to work for any values between it. Similar to Mathematical Induction. So, this applies for programming too.

If you are able to identify the boundary conditions, and make the appropriate formula for those conditions, then you will skip unnecessary computations.

We will look what have save the computational cycles.

Lets assume, the Input are N=10, K = 2

Using Solution-1:

residue = 0, mid = 5

maxProduct = Math.pow(5+1,0) * Math.pow( 5 ,(2-0) ) = 25

Operations performed:

Note: costs are just for calculation, not exact one

• Math.pow
• Addition – (5+1)
• Math.pow
• Subtraction – ( 2-0 )
• Multiplication

lets assume the cost for each operation is

Using Solution-3:

The code will branch out to the 1st if condition ( residue == 0 )

maxProduct = Math.pow( 5, 2) = 25

Operations performed

So, you have saved more than 55% of the computational cycles by covering up the boundary conditions.

So, Why you need a Speedy code?

Everyone in life loves speed. Speed bike, Speed cars ( that’s why you would love F1 ), A speedy 2 GB – Core 2 Duo Powered Machine.

Because Speed makes you feel Good !! So does a Speedy Code will be a Good code.

But, to achieve something you have to compromise with other factors, like I mentioned earlier.

If you need a 2 GB – Core 2 Duo Powered Machine, you should not consider the Money factor.

Similarly while you code, there are lot of other factors like

• Memory Management
• Security
• Transaction Isolations etc.,

This is just a introduction, will start covering up other topics soon.

 Annoyed with constant pings of Twitter messages in your GTalk? Floated with loads of Email from Digg friends request and Shouts? You get mail from Pownce filling up your inbox just by covering up your important mails? Here is a solution for you to get free from all those annoying stuffs, but still you want to get all the updates as like before? And finally you have problem tracking all the online application’s information daily? Ok ok..I stop at this point and will take you my post.

FriendFeed offers amazing facility that lets you merge a list of online application into one feed to track.

Yo! that’s cool. About 28 frequently used web applications!

Get your info across all the web applications merged into one and read it at some point of time when you want to read it.

This is my feed which has got Twitter & Pownce merged into one , which really makes me free out of all those annoying pings!!

Yeah really, this would save you a lot of annoying pings, emails and messages. You can now turnoff your notification in Digg, Pownce and twitter and still get updated through the Rendered.

Once you have created your feeds, FriendFeed combines everything into a RSS feed send a one time email notification either daily / weekly.

Or put FriendFeed into your Facebook,

or even into your Google reader or any of the RSS feed reader application.

Courtesy: Yi Shiang

A Comprehensive list of most useful Windows Run Commands before you.

For quick windows commands Read on How to use Shell Operator

Make use of it and hack the features of Windows XP for better and productive use.

Courtesy:zackv

You would have explored the features of GMail Search in my previous post Hack GMail – Part 1

In my previous post of hacking the search, you  would have explored the features on Labels, filters etc. On continuing the exploration, I came with my second post. This post lists down the features which are not available in the simple search facility. Come one, lets explore the the advanced search features.

For typing the query, you need not open the simple search view, just directly type the query in the default query box.

In order to be a master in searching, you have to know the operators used for searching. To know brief about the operators have a visit to

https://gmail.google.com/support/bin/answer.py?answer=7190

Also have a look on how to create filters and labels. This is a must use tool in Gmail, who fail to use these features, so pity on them. Please don’t miss it out.

https://gmail.google.com/support/bin/answer.py?answer=6579

In the rest of this blog, you could find the functions of the operators in elaborate.

from: used to specify the sender and fetches all the mails from the same

It is the same as the from in the simple search.

Example 1: Extract all the mails from friends, say abc,abc1,abc2. Then your query goes like this.

from: abc@hotmail.com OR abc1@yahoo.com OR abc2@gmail.com

Example 2: Extract all the mails from friends, say abc,abc1 and not from abc2. Then your query goes like this.

from: abc@hotmail.com OR abc1@yahoo.com -abc2@gmail.com

Example 3: Extract all the mails from except from abc

from: -abc

Example 3: Extract all the mails from except from yahoo or gmail

from: -yahoo.com –gmail.com

to

: used to specify the recipient and fetches all the mails from the same. It is the same to the TO in the simple search.

Example 4: Extract all the mails sent to friends, say abc,abc1,abc2. Then your query goes like this.

to: abc@hotmail.com OR abc1@yahoo.com OR abc2@gmail.com

Example 5: Extract all the mails sent to groups i.e mails your received from groups.

to: yahoogroups.com

Example 6: Similarly exclude the mails from yahoogroups

to: -yahoogroups.com

subject: Search for the subject words

Example 7: Search for a single word

subject: Chennai

Example 8: Search for more than one word. In this example to include all mails with subject Chennai and Mumbai and reject mails with subject kolkatta

Subject: ( Chennai OR Mumbai ) subject: –kolkatta

cc and bcc: This operator function similar to the to: and from: operator. It is used to give the email address or just the account name or just the service provider address to fetch the mails.

Example 9: Fetch all the mails which you had CCed or BCCed

cc:abc@yahoo.com
bcc:abc1@yahoo.com

label: Search the mails which holds a label.

Example 10: Let me assume that you have labels and have applied to some mails. Let me say you have label called “Family” for the mails which you receive from your family members. Now you are to search for the mails where only your mom had sent. Here I am considering that both dad and mom uses the same mail id.

label:family from:familyhead@gmail.com mom OR dad

Example 11: Another example to show is from my inbox. I have grouped all the fun related mails from various groups such as Nidokidos, myWorldPals etc. under the label named “Others”. Now all the mails arriving from that group would be fixed with the label “Others”. Now I need to search the mails from this label, which has photos regarding “Katrina”.

label:Others (subject:nidokidos OR myworldpals)

Another example which rejects all mails with subject beautifulIndia.

label:Others subject:-BeautifulIndia

Note: If you have label names separated with spaces, then use hyphen(-) while using in searches. The Hyphen, i.e the negation operator is different from this hyphen used in the label names.

E.g.: If you have a label called “Fun Mails”, then while searching use as label:Fun-Mails. Here note that there is no space in between Fun & Mails. If you introduce a space, then the query will search for the mails with label Fun and rejects all mails with words Mails.

i.e. label:Fun –Mails

It is possible to apply one or more label name to a single mail. Example, if you have received a mail from your friend relating to a job matter, then you would apply labels both Friend and Jobs. In such cases, most of the mails may posses more than one label. Now in such cases to search mails pertaining to particular label and rejecting the mails the label you are not in need. The simple figments is to use Negate Operator i.e Hypen.

Example 12: You need to extract all mails from your friend which don’t have job information i.e don’t have label named JOBS.

label:friend –label:JOBS

Example 13: Search all the mails from your friend with attachment, which has only Word document or PDF files as the attachments.

label:Friend has:attachment filename:(pdf OR doc)

in: used to search mail in the specific location i.e Inbox, Archives, Trash, Sent Items etc. If you are in need to search locations except Inbox, you could use this operator.

This operator had really helped me to search in my case, as I had about 30,000+ mails in my trash.

Example 14: Searching your trash box for a which you have deleted it unknowingly. All mails from your friend that had moved to trash.

in:trash label:friend

Now you can combine all the above said operators to search the mail.

Example 15: Search your trash and archives which you are not confident about it’s location which has an attachment of pdf file from your company.

in:anywhere has:attachment filename:pdf

is: Is operator is helps you to fetch mails that have read, unread , starred etc.

Example 16: To fetch all mails that you haven’t read that your friend had sent.

label:friend is:unread

Try with is:read is:unread, yeah you can guess what would be the result.

is:read – gives all the mails that have read

is:unread – gives all the mails that haven’t read

is:starred – gives all the mails that have been starred in spite you read or not.

after:, before: These operators are date operators which are used to input the query based on date values. The date format which I have aforesaid in the first part as YYYY/MM/DD is used.

Example 17: To search all the mails which have arrived after June 4^th 2005. to till date.

after:2005/06/05

Example 18: To search all the mails arrived on particular date, use both the operators

after:2005/09/10 before:2005/09/11

If you use after:2005/09/10 before:2005/09/10, will gives you all the mails.

Here’s how to do it in windows:
1. Click Start
2. Click run
3. In the run box type cmd.exe and click OK
4. When the command prompt opens type the following. ENTER after each new line.

ipconfig /flushdns
ipconfig /release
ipconfig /renew
exit