I am kind of weak in probability and permutation & combination. But I don’t have time to go through entire textbooks. Is there compact tutorial or any site where I can all the concepts.

Well tutorials will not give the required exposure as a text book , as these are fundamental and big topics . There are lots of areas within them with quite a many formulas , I would suggest that you go for reading a text book on each topic . Reading a tutorial here and there will not help much . That’s my opinion .

can you suggest some good books ?

**A path to Combinatorics for Undergraduates** by Titu Andresscu, Zuming Feng

There is also one book by Knuth, I dont recall the exact name.

Discrete Mathematics by C.L. Liu ( from Tata Mc Graw Hill publishers , hence very affordable ) is very good book , it will cover combinatorics and basic graph theory also . Also there are things like recurrence relations which you need time and again . I don’t remember a good probability book now but i will search and let you know .

@bugkiller: Maybe you are referring to Knuth’s “Concrete Mathematics” book ? It’s pretty good for the combinatorics part and it also has a chapter on probabilities. It’s worth checking out and it’s freely available on the Internet: http://www.maths.ed.ac.uk/~aar/papers/knuthore.pdf