many times i come up with solution some times the solution is brute force and some time it is optimised one. but onces i am done with the problem.(i.e accepted) one question is always strick in my mind that WHY MY SOLUTION IS TRUE.. how do i proof that it is always give me the correct ans....... so that is why i am always in delema that i dont understand the problem and solution well enough SO ANY SUGGESTION..(my english is weak XD sorry!!)