Problem Solving and Thinking

Well I will be talking in Programming aspect. When you try to solve a problem this may happen in most of the time you are able to understand the problem fully but when there is a time boundation this may happen that the implementation is not complete. So, I am searching where is the problem even when I know most of the part of implementation. I came to the result that it's applying all those functions, which are returning something but when I tried to apply them then I was not able to apply them effeciently. The problem understanding is simple but when it comes to apply that thought there is something missing out which is lack of practice.
How to think about a problem?
This is the question which arises in my mind most of the time. How we get the understanding and try to implement that in that respect. Eventhough the thinking of different people is different but we get the same result.
Critical thing
When there is a time boundation to do a programming task, I din know about other minds but my mind gets somewhat I couldn't explain. The problem which I was not able to clear, I was there with the solution. How?????????????????????????????
I would not like to ask Why??????????
As that thing did for me.
So overall I would like to say if you are performing a Programming Task better you should be bound with a time limitation so that there should be a stress on your mind.