What is the principle of ranking query on webmaster tools? How to solve it

What is the principle of ranking query on webmaster tools?
Website: http://tool.chinaz.com/KeyWords/

He can check at most 100 Baidu Snapshot (a page 10, that is, 10 pages,), if each time with file_get_contents read the page, and then match, a query 100 is also a file_get_contents Baidu 10 pages, the speed will be very slow , but why is the speed of this stationmaster station so fast? What is the principle of use? And not only this one station has this function, many stationmaster station has, I think Baidu certainly will not give him to provide API interface! What's his principle, why so fast?

------Solution--------------------
You can see the first 100 records at one time without the API.
For example, query csdn URL rules: www.baidu.com/s?wd=csdn
You can see the first 100 records, such as www.baidu.com/s?wd=csdn&rn=100, by adding a parameter &rn=100.
------Solution--------------------
Remove 100 directly, then extract

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