A fairly interesting math problem from Project Euler.

By far, this path question is the only one I put some thought in it, other problems' answer are found in less than 5 minutes each.

Best idea when meeting problems like this is to change geometric objects into algebra objects.
so there is a function, f(x), which will produce the amount of paths for a x*x block.
f(1) = 2, I tried it by drawing it out
f(2) = 6, given
any patters? not really.
I don't want to get into programming to solve this problem because I can see this does not need brute force attack, it can be solved by a equation for f(x)
now, I have to introduce another function, g(x,y), where x is the width of the blocks and y is the length of the blocks. it's easy to see the special case for this function, when x=y, is f(x).
with a little reasoning, g(x,y) = g(y,x) can be deducted, because after a rotation, the shape is the same.
there are only 2 choices for the first step, either going toward the end point by following horizontal line or the vertical line. after that, the problem deduce to a (x-1)*y or a (y-1)*x block. A inspirational found, because following recurrence will save the day
g(x,y) = g(x-1,y) + g(x,y-1)
Find the explicit formula for this recurrence and you can solve for the answer.

No offense, but the name "Instantbird" isn't that cool when compete with Firefox, Thunderbird and SeaMonkey, try something else ("Razorcow" sounds nice).

While I was downloading the 13MB install package for windows, I will tell you about what else I'm using for IM.
I have used Meebo, before I meet Pidgin.
Pidgin replaced Meebo because javascript is just too slow to handle 300+ contacts on all my IMs. The only fault of Pidgin is it's using some processing power, quite slow and uses GTK (optionally aspell). Of course I have nothing against GTK, but install GTK (and Aspell) just for Pidgin sounds a bit clumsy to me.
Miranda IM is another choice, it's fast, lite and efficient, but it's interface pisses me off, it's too simple and not humanly accessible.

Instantbird suppose to steal away my heart, the release of 0.1 show the basics of the frame, but it is in no way or shape for anyone to abandon what you are using now, for god's sake, there is no option to format your text yet!

I did not blur anyone on my contact list... I really don't think anyone would add people on my contacts
Reasons for looking forward to Instantbird's future include:
-XUL Technology, what firefox use
-Mozilla behinds the project