Where did you get 1G?

Post #273,996 by tuberculosis 11/26/06 10:47:19 PM 11/26/06 10:50:05 PM Reply	Where did you get 1G? SSNs are 9 digit numbers. There are a billion possible. You need 10 bytes to store one based on the scheme you mentioned. So you need 10G worst case to store the data. What is the efficiency of your algorithm. IOW, as n increases, what happens to search time t? How fast can you grep a 10G file? If its more than a few milliseconds it is too slow. Having and being able to explain these numbers will get you a second interview. Not having them will get you a 'thanks for your time'. Its not even remotely academic in that environment. You have to do this kind of stuff with all kinds of data. Session ids, customer ids, sku codes, etc. For fun, generate the file of all possible numbers, then grep 500000000. That's your average. Let me know how long it takes. [link\|http://www.blackbagops.net\|Black Bag Operations Log] [link\|http://www.objectiveclips.com\|Artificial Intelligence] [link\|http://www.badpage.info/seaside/html\|Scrutinizer] Edited by tuberculosis Nov. 26, 2006, 10:50:05 PM EST Where did you get 1G? SSNs are 9 digit numbers. There are a billion possible. You need 10 bytes to store one based on the scheme you mentioned. So you need 10G worst case to store the data. How fast can you grep a 10G file? If its more than a few milliseconds it is too slow. Having and being able to explain these numbers will get you a second interview. Not having them will get you a 'thanks for your time'. Its not even remotely academic in that environment. You have to do this kind of stuff with all kinds of data. Session ids, customer ids, sku codes, etc. For fun, generate the file of all possible numbers, then grep 500000000. That's your average. Let me know how long it takes. [link\|http://www.blackbagops.net\|Black Bag Operations Log] [link\|http://www.objectiveclips.com\|Artificial Intelligence] [link\|http://www.badpage.info/seaside/html\|Scrutinizer] Collapse All History
Post #274,000 by Another Scott 11/26/06 11:08:48 PM Reply	Not all 9 digit numbers are valid. As I'm sure you know. [link\|http://en.wikipedia.org/wiki/Social_Security_number\|Wikipedia] Valid SSNs Currently, a valid SSN cannot have an area number above 772, the highest area number which the Social Security Administration has allocated.[3] There are also special numbers which will never be allocated: * Numbers with all zeros in any digit group (000-xx-xxxx, xxx-00-xxxx, xxx-xx-0000). * Numbers of the form 666-xx-xxxx, probably due to the potential controversy (see Number of the Beast). Though the omission of this area number is not acknowledged by the SSA, it remains unassigned. * Numbers from 987-65-4320 to 987-65-4329 are reserved for use in advertisements [citation needed]. The Administration publishes the last group number used for each area number. Since group numbers are allocated in a regular (if unusual) pattern, it is possible to identify an unissued SSN that contains an invalid group number. Despite these measures, many fraudulent SSNs cannot easily be detected using only publicly available information. Thus, at the moment, there are a little less than 772M possible valid SS numbers. Hey, a 22% savings is nothing to sneeze at! :-) Cheers, Scott. (Who would probably answer a question like this by saying: "I'm sure this is a well-known problem that has been solved many times over the last ~ 70 years. Give me a few minutes with Google and I'll get back to you." - because he's not a programmer.)
Post #274,003 by tuberculosis 11/26/06 11:15:44 PM Reply	I assumed so but I didn't know what the rules were. There is also, the obvious 50% optimization. If more than half the numbers are allocated, I only track those that are not. Otherwise I track those that are. Thus my worst case scenario moves to 50% allocated and my memory requirements are potentially cut by half. [link\|http://www.blackbagops.net\|Black Bag Operations Log] [link\|http://www.objectiveclips.com\|Artificial Intelligence] [link\|http://www.badpage.info/seaside/html\|Scrutinizer]

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