hashcode

How to find an distinct URL only in set A not in set B.

There are two sets of URL, both contains millions of URLs. Now, How can I get an URL from A that is not in B. What's The best methods? Note: you can use any technique, use any tools like database, mapreduce, hashcode, etc, . We should consider the memory efficient, time efficient. You have to consider that every set (A and B) have millio...

Is any substring of an encrypted hash (md5, sha1) more "random" than another?

Here's 3 example md5 hashes $ md5 -s "1" && md5 -s "2" && md5 -s "3" MD5 ("1") = c4ca4238a0b923820dcc509a6f75849b MD5 ("2") = c81e728d9d4c2f636f067f89cc14862c MD5 ("3") = eccbc87e4b5ce2fe28308fd9f2a7baf3 Say I wanted to take 8 characters from any hash. Is the beginning part of the hash particularly more "random" than the end? middle? ...

how can i decode this base64 code?

im sorry if this is a stupid question but i was curious, i have this code that translates into my name im wondering what hash function its using, i thought it was md5 this is my name: saleh and this is the code 9LjZ6QoOB1A%253d pleaaase help ...

what is the preferred way of implementing hashCode()?

Sometimes I need to implement an obj's hashCode() method by combining the hashCodes of its several instance members. For example, if the combinational obj has members a, b, and c, I often see ppl implement it as int hashCode(){ return 31 * 31 * a.hashCode() + 31 * b.hashCode() + c.hashCode(); } Where does this magic number 31 come...

Finding the hash value of a row in postgresql

Hi, Is there a way to get the hash code of a row in postgresql? I need to export some data only if there is some changes in the data after the last export, the last exported data rows can be stored in a table, the when the again I need to export the data I can get the hash values of all the data and export only those rows who has a d...

wpf overriding getHashCode and Eqaul in ContentControl

Hi I have a class which derives from ContentControl and I'm not able to override GetHashCode and Equal method. I get an error Error 5 cannot override inherited member 'System.Windows.DependencyObject.GetHashCode()' because it is sealed Is there any way to override this method ? I need to use Union method from LINQ however I need to c...

Boolean.hashCode()

Now I see how to implement a method hashCode() for the Boolean object: public int hashCode() { return value ? 1231 : 1237; } And I wonder why it returns a values 1231 or 1237, why not something else? ...

Override equal's and hashCode for abstract super class

Consider the sample code given below: Abstract Name public abstract class Name { private String name; public Name(String name) { this.name=name; } public String toString() { return name; } public String getName() { return name; } } FirstName public class FirstName extends Name { FirstName(String name) { super(...

Good hash function for list of 2-d positions?

Hi! I have a series of objects whose only different internal state is a fixed-length list(or whatever) of 2-d positions (2 integers). That is, they all have the same number of elements, with (potentially) different 2-d values. I'm going to be constantly comparing new instances against all previously existent, so it's very important tha...

How do I hash a 2-d array efficiently (to be stored in a HashSet)?

I've written a class called PuzzleBoard that represents an nxn board. I will be keeping several PuzzleBoard objects in a HashSet, so I have to overwrite the 'int hashCode()' method. Below are the fields of my class: private int N; private int[][] puzzle; private int blankCellX; private int blankCellY; private int cost; What Ecli...

Using ToHashCode to store hash in database?

We are currently extensively using the GetHashCode method to store hash codes in a database for tracking unique items. MSDN has a scary entry about this here "The default implementation of the GetHashCode method does not guarantee unique return values for different objects. Furthermore, the .NET Framework does not guarantee the default ...

For HashMap, would implementing hashCode() for the value help if I only search by key?

I'm using Java 6. For simplicity, everything will be public. Suppose I have this simple class. public class A{ public String name; public String data; } I want to put my class A objects into a HashMap. I will use the field name as the key, and the whole object as the value. I will only search for an object in this map by na...