Some other resources besides CLRS...

Free interactive Python textbook on Algorithms & Data Structures: http://interactivepython.org/courselib/static/pythonds/index...

Robert Sedgewick and Kevin Wayne of Princeton have a great textbook (code samples in basic Java): http://www.amazon.com/Algorithms-4th-Edition-Robert-Sedgewic...

They also teach a two-part Algorithms course on Coursera: https://www.coursera.org/courses?orderby=upcoming&search...

Thomas Cormen (the C in CLRS) also has a new book called Algorithms Unlocked which introduces some popular algorithms in pseudocode. http://www.amazon.com/Algorithms-Unlocked-Thomas-H-Cormen/dp...

Coursera, no doubt. I took 2 courses with Tim Roughgarden; they were awesome. And I just finished 2 more with Sedgewick. If you can find the Sedgewick courses, I recommend picking up his book (actually, I recommend it anyway) - Algorithms, Sedgewick & Wayne, 3rd ed.

Also, there's a book site for the Sedgwick & Wayne book:

http://algs4.cs.princeton.edu/home/

There's a lot of good stuff.

Try the video course that goes with the Cormen book on Algorithms. You can start it right now, its not a scheduled course like Coursera but more a repository like Khan.

http://ocw.mit.edu/courses/electrical-engineering-and-comput...

The math behind this stuff is in the first third of most calculus textbooks. The CS half can be found in CLRS. You can also probably learn it from TopCoder tutorials or usacogate (I recall there being a mirror of usacogate that did not require you to do all of the problems in order to advance).

CLRS? Why you young whippersnapper! Back in my day it was called CLR, and those three letters were good enough for us! Kids these days...

mmanfrin, it's this book: http://en.wikipedia.org/wiki/Introduction_to_Algorithms

The book along was a little terse for me. The videos from OCW however are priceless, even entertaining sometimes.[1]

[1] http://ocw.mit.edu/courses/electrical-engineering-and-comput...

I'm very bad at calculus , but I can work out Big O intuitively quite easily.

Even average case complexity?

Enough to guess with a fairly high degree of accuracy.

Only for the simple stuff (and that might be good enough for you). Average case complexity is devilishly hard in general, and even worst case complexity is super hard. E.g. try analysing fibonacci heaps `intuitively'.