give the problem just one hour then start reading the editorials. you can find detailed answer here

if u don't have quora account, this is the answer... The best strategy I have found to get good at TopCoder is: 1) Pick a problem to solve and spend an hour trying to solve it. If you solve it or you are stuck at the end of the hour move on. If you solve it in less than 10 minutes the problem was too easy, go find a harder problem and repeat this step. 2) Read the editorial for the problem. 3) Read the code of high ranked TopCoders. Their code will probably be shorter and simpler than yours. Figure out how they did it. 4) Code the problem (or improve your first solution) using what you have learned to write a simple solution. 5) Go to step 1.

The reasoning behind the steps: 1) Spending more than an hour or two on a problem is generally a waste of time. There are some types of problems that are extremely difficult to solve the first time you see them. Rather than spending a ton of time just skip to reading the solution. It is also very hard to stay motivated when you are stuck on a problem after a couple hours. 2) Reading the editorial is useful even if you solved the problem. There could have been other approaches that you didn't think of. 3) The key to being fast isn't typing quickly, it is writing code without bugs. The best way to not write bugs is to write simple code. The best TopCoders write simple and short code so learn from them. 4) Going back and coding the problem again will make sure you really understand the problem and how to code it.

Just have fun. If you are bored, trying to solve a problem — read editorial. If you are enjoying process — continue to do it. One week, one month — does not matter. If you are not interesting in solution — skip this problem. Once you will face it in an actual competition or learn related theory and you will become more motivated to solve it.