how can i decide with google search results for article title, if uploaded article not copy of existent article in other website?

Question

Hello,

I have to check for uploaded articles by the user if they not plagiarized (copy of existent article in other websites).

I planning to take title of new uploaded article to my website and search in google to find out if exist already same article.

the problem:

How can i decide with google search results for article title, if uploaded article not copy of existent article in other website? (I will write php script that will discover auto)

please if you already exist php script or in other langauge that do it it will be great, but more important to me is discover right algorithm to do it.

Thanks you very much!

Bobi