Is it okay to assign free marks for students assignments? Regarding to a course for undergraduates (especially in computer science, but i would love to hear opinions from others too):

Is it okay to assign free marks for assignments? Meaning, the students who submitted the assignments will be assigned full marks. 

If yes, in total how much percentage of free marks you assign from the overall 100% of the course? Is 30-40% too much?
How many assignments do you give? 

This is because, students tend to discuss or copy paste the assignments from friends. And I don't want them to do that because of fear of losing marks. When I say I don't deduct marks for a particular exercise, I see that some students are willing to take the challenge and be creative with their answers, although their answers sometimes are wrong. I believe that people learn from mistakes.

But people might question me if I just give them full marks for 30~40% from the overall course marks. I couldn't measure whether I am too lenient, unbelievable, too dumb, etc, because of lack of experience.

So please, any opinion would be appreciated.
This heavily depends on your country, institution and position (most professors can get away with everything in regard of teaching if they research well).

In my country in Central Europe, this strategy is in universities not unheard of (because of the arguments you mention). One of my high school teachers even claimed that she is not allowed to give marks about the content of the homework, only about whether we did it in time, read the assignment careful and wrote comprehensively.

Of course, you could also make the homework weigh less.

Personally, I like this approach if you not mark the contents but whether or not they tried the tasks in a reasonablr fashion.