如何从给定的四个数字中生成一个唯一的数字，以及如何从生成的唯一数字中获取这些给定的数字？

Question

I was using a Map(String,Integer) in java. Keys were generated from string concatenation of four given numbers.

givenNumber1 at most 6 digits, givenNumber2 at most 4 digits, givenNumber3 at most 4 digits, givenNumber4 at most 4 digits.

Because of memory cost, I want to use Map(Integer,Integer) in java. Now how can I generate an unique number from given four numbers and then how to get back these four numbers from this generated number?

Is there an efficient(memory,cpu) way to do it?

Answer 1

Integer.Max is 2,147,483,647(10 digits) and in your example you want to put 6 + 4 + 4 + 4 digits so your max number is much bigger that max int 10 digits vs 18 digits.

So it's impossible to simply replace you map from Map < String, Integer > to Map < Integer, Integer>