I want to join good product based company so how can apply for this.
It may depend your experience. Product company is good choice.
If you are fresher, do a very simple thing. Pick the domain ( Retail to Robotics) , take general problem and put a half page writeup how would you solve. Few things to keep in mind.
1. NOT too long ( half a page text with 2 simple diagrams) . Attention span reduce with the length.
2. It should be original. (Expect more questions in interview)
3. State your assumption at the last. These are important.
4. Everything else ( resume) etc are still relevant.
Product development need people with commitment. Usually only after 2-4 years you can contribute to product in meanigful way. (Worked for 14 yrs, can not emphasis more on than this)
Fore example :- A simple problem in Retail would be " How many cash Counters you need? "
It may look a math problem to you like X cash counter and Y mins per person hence X*Y. But this becomes tricky if you read about this and figure our that concerns are
1. People/Employee cost money
2. Time at cash counter is inversly proportional to customer satisfaction.
3. People with less items tend to give their purchase ??
What are the ways you think you can solve/help. Putting meaningful ans in half page will extremly time consuming but distinguishing feature.
You can put this into cover letter after briefly giving your profile (Fresher usully dont have cover letters but it will be good to have one).