One of economic theory belief population growth is not a problem because you will have more people to think and have solution, do you agree?

Population growth is intrinsically an economic advantage.   The population of the world has grown from2 (average net worth, $0)  to7 billion (average net worth, $20,000+).

no, population is it self a big problem, in the world, million's of people die, because of malnutrition , and various diseases, were there is no cure for it.

I agree with this statement but it is associated with a proper handling of resources like Human resource. It can only be achieved with the help of a good management. China is a great example of such an economy that has population over a billion.