
MIT’s Introduction to Algorithms, Lecture 3: Divide and Conquer - ajbatac
http://www.catonmat.net/blog/mit-introduction-to-algorithms-part-two/
======
aston
The killer concept to grok with divide-and-conquer is that it's only powerful
if

    
    
      1) the smaller version of the problem is actually
         easier to solve and not just smaller
                      - or -
      2) the smaller version of the problem is just as 
         hard to solve, but you can combine smaller versions into
         a bigger one with less work than doing the bigger itself.
    

Quicksort is an example of the former (partitioning a list of size 2 or less
_is_ sorting it, even though partition is linear time). Merge sort is too
(combining two sorted lists is linear time). Repeated squaring is an example
of the latter, as is the Strassen matrix multiplication.

I took this class, and it took me a lot of just sitting around pondering
before I got that stuff.

~~~
pkrumins
Thanks for your insightful comment! Can I use it in my post? (full credit to
you)

~~~
aston
Yeah, definitely.

------
tristmegistus
For the very interested the course website is
[http://ocw.mit.edu/OcwWeb/Electrical-Engineering-and-
Compute...](http://ocw.mit.edu/OcwWeb/Electrical-Engineering-and-Computer-
Science/6-046JFall-2005/CourseHome/index.htm). It has the videos, lecture
notes, problems sets and solutions. I missed the link on Peteris' review.

~~~
pkrumins
Oh, the link is in the 1st post of the review series! Didn't feel like
including it in every post. Perhaps I should.

~~~
brent
_The last topic covered in this lecture is VLSI (Very large Scale Integration)
layout problem: given a number of various electronic gates an chips, how to
position them on the circuit board._

You may want to state the objective here as well. I haven't seen the lecture,
but from the still on the google video I presume it is "... how to position
them to minimize area".

~~~
pkrumins
Oops, sure, how to minimize area. I had these words in mind when I was writing
the post. Fixed now. Thanks! :)

