Examples of CPU intensive, memory intensive, I/O intensive C code required

Can someone please post c codes which are either memory intensive, cpu intensive or I/O intensive , atleast 1 example of each, And please keep the codes as small as possible....

Thanks and regards
Shivam Sharma

Please read the FAQ to see why we wont do your homework for you.

I am not asking u to write down the whole code u can simply tell like the algorithm for Optimal binary search tree is CPU intensive or some other sort is memory intensive.... I am just asking you to write down a few examples