CODEWITHSUNDEEP
hash
tonicebrian
tonicebrian

Reputation: 4795

Fast way to hash a tuple of integers

I need to hash tuples of integers (order is important) into integers with low probability of collision. I'm using the approach of converting integers to string, concatenate with ',' and obtain the string hash but it's being too slow.

Is there a way for getting fast hashes from tuples of integers?

Upvotes: 6

Views: 2351

Answers (1)

Thilo
Thilo

Reputation: 262534

Here is what Java's Arrays.hashCode(int[]) does:

 2938       public static int hashCode(int a[]) {
 2939           if (a == null)
 2940               return 0;
 2941   
 2942           int result = 1;
 2943           for (int element : a)
 2944               result = 31 * result + element;
 2945   
 2946           return result;
 2947       }

This calculation is specified in the List interface. I don't know if it is collision-resistant enough for you, but it seems like a good place to start. It does take order into consideration (i.e. different order of the same numbers will yield a different hash value).

Upvotes: 4

Related Questions