How to recognize table from PDF files by PageObject Rectangles?

I want to recognize tables inside PDF, now I have rectangles of the PDF Text Object.I'm confused about how to implement this rectangle algorithm. The programming language what I use is VC++.

What I want to get is:The Result is a perfect table with header, rows, columns.Can anyone help me? How to rectangle table from these rectangles? These rectangles' orginal point (0, 0) is on the bottom-left point. x coordinate grow from left to right, and y coordinate grow from bottom to up.I don't want to use 3rd party. I want to implement this function through rectangle algorithm.

Any help would be greatly appreciated!