How to calculate order (big O) for more complex algorithms (ie quicksort)

Posted by bangoker on Stack Overflow See other posts from Stack Overflow or by bangoker
Published on 2010-04-12T23:37:12Z Indexed on 2010/04/12 23:42 UTC
Read the original article Hit count: 328

Filed under:

big-o

|

algorithm

|

complexity

I know there are quite a bunch of questions about big O notation, I have already checked Plain english explanation of Big O , Big O, how do you calculate/approximate it?, and Big O Notation Homework--Code Fragment Algorithm Analysis?, to name a few.

I know by "intuition" how to calculate it for n, n^2, n! and so, however I am completely lost on how to calculate it for algorithms that are log n , n log n, n log log n and so.

What I mean is, I know that Quick Sort is n log n (on average).. but, why? Same thing for merge/comb, etc.

Could anybody explain me in a not to math-y way how do you calculate this?

The main reason is that Im about to have a big interview and I'm pretty sure they'll ask for this kind of stuff. I have researched for a few days now, and everybody seem to have either an explanation of why bubble sort is n^2 or the (for me) unreadable explanation a la wikipedia

Thanks!

© Stack Overflow or respective owner

Related posts about big-o

Big Data – Learning Basics of Big Data in 21 Days – Bookmark

as seen on SQL Authority - Search for 'SQL Authority'
Earlier this month I had a great time to write Bascis of Big Data series. This series received great response and lots of good comments I have received, I am going to follow up this basics series with further in-depth series in near future. Here is the consolidated blog post where you can find all… >>> More
Big Data – Beginning Big Data – Day 1 of 21

as seen on SQL Authority - Search for 'SQL Authority'
What is Big Data? I want to learn Big Data. I have no clue where and how to start learning about it. Does Big Data really means data is big? What are the tools and software I need to know to learn Big Data? I often receive questions which I mentioned above. They are good questions and honestly when… >>> More
Big Data – Various Learning Resources – How to Start with Big Data? – Day 20 of 21

as seen on SQL Authority - Search for 'SQL Authority'
In yesterday’s blog post we learned how to become a Data Scientist for Big Data. In this article we will go over various learning resources related to Big Data. In this series we have covered many of the most essential details about Big Data. At the beginning of this series, I have encouraged… >>> More
Big Data – Is Big Data Relevant to me? – Big Data Questionnaires – Guest Post by Vinod Kumar

as seen on SQL Authority - Search for 'SQL Authority'
This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions of SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect… >>> More
Big Blue Bets Big on Red Hat's Virtualization Technology

as seen on Internet.com - Search for 'Internet.com'
Virtually Speaking: In the next battleground for the cloud, IBM's choice of Red Hat's virtualization technology may be changing the landscape, but don't count VMware out just yet. >>> More

Related posts about algorithm

Jpeg Algorithm vs BMP Algorithm?

as seen on Super User - Search for 'Super User'
I'm just wonder, what the differences are between creating a BMP file algorithm and JPG file algorithm ? If you know the others images' format algorithm, please post them. Thanks. >>> More
word disambiguation algorithm (Lesk algorithm)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hii.. Can anybody help me to find an algorithm in Java code to find synonyms of a search word based on the context and I want to implement the algorithm with WordNet database. For example, "I am running a Java program". From the context, I want to find the synonyms for the word "running", but the… >>> More
Search algorithm (with a sort algorithm already implemented)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, Im doing a Java application and Im facing some doubts in which concerns performance. I have a PriorityQueue which guarantees me the element removed is the one with greater priority. That PriorityQueue has instances of class Event (which implements Comparable interface). Each Event is associated… >>> More
Is there any algorithm for finding LINES by PIXEL COLORS on picture?

as seen on Stack Overflow - Search for 'Stack Overflow'
So I have Image like this I want to get something like this (I hevent drawn all lines I want but I hope you can get my idea) I need algorithm for finding all straight lines on it by just reading colors of pixels. No hard math, no Haar, no Hough. Some algorithm which would be based on points… >>> More
collsion issues with quadtree [on hold]

as seen on Game Development - Search for 'Game Development'
So i implemented a Quad tree in Java for my 2D game and everything works fine except for when i run my collision detection algorithm, which checks if a object has hit another object and which side it hit.My problem is 80% of the time the collision algorithm works but sometimes the objects just go… >>> More