Bijective hash function

Question

The function that returns the hash can return the same index for different id values:

hash(id) = id%ARRAY_SIZE

Is there a way to have the hash function being bijective. I thought of:

hash(id) = id

But I do not have contiguous id values. Does someone have a better solution ?

score 2 · Accepted Answer · answered Aug 23 '16 at 09:59

2

A hash function is any function that can be used to map data of arbitrary size to data of fixed size.

So by definition, a hash function cannot be bijective, because its domain is infinite, while its range is finite.

answered Aug 23 '16 at 09:59

Tamás Zahola

5

While true, for any fixed finite set of inputs there does exist a perfect hash. – R.. GitHub STOP HELPING ICE Aug 23 '16 at 11:50

1 Answers1