How to mathematically determine the unique number for any two in64?

A

Anatoly602015-03-17 00:34:09

Mathematics

Anatoly60, 2015-03-17 00:34:09

Is it possible to get a number using bit operations that is guaranteed to be unique for any two arbitrary numbers (int64)? In this case, this number must also be int64.

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2 answer(s)

B

bobrovskyserg, 2015-03-17
@bobrovskyserg

Well, how can I tell you, Dunno ...
Why the hell are we spending money on 2 arbitrary int64 numbers, when they could be crammed into one int64.
So think...
1 bit contains 1 bit of information.
2*64bit contains 2*64 bits of information.
Oh, Shannon, to whom have you left us!

M

Mercury13, 2015-03-17
@Mercury13

You can't, simple combinatorics.
One number - ²⁶⁴ options, two numbers - ²¹²⁸ options.
The Dirichlet principle says that in one of the cells there will not even be two rabbits, but at least ceil(2 ¹²⁸ / 2 ⁶⁴ ) = 2 ⁶⁴ rabbits - that is, for some answer there will be at least 2 ⁶⁴ pairs of arguments that give it.