Question

I am reading XOR linked list (from Wikipedia).But I am having some problems in understanding it.

I am not getting following paragraph.

To start traversing the list in either direction from some point, you need the address of two consecutive items, not just one. If the addresses of the two consecutive items are reversed, you will end up traversing the list in the opposite direction.

I have few questions about it :

1. How does it (the XOR linked list itself) actually work ?

   (It would be great if you justify your answer by giving some example.i.e
   by taking some addresses and then
   doing some calculations accordingly.)

2. How can I implement it? A brief idea about implementation.

3. Practically where it is or can be used? Is it really helpful as it seems?

Answer 1

1. The above procedure works by storing the addresses of both the next and previous elements in one field (let’s call it A). Therefore, to get the value of the next element in the list you take the address of the other element you have (which is why you need two…call it B). To find the address of the next element, you just A XOR B to get C (the location of the next element).

2. Depends on what language you’re using. Study up on bitwise operations in whatever language you’re using and you should be able to figure it out pretty quick.

3. It can be used anywhere you use a double-linked list (the XOR linked list will save memory). The caveat being that you have to have two sequential elements of the list to traverse through the elements.