37 lines
1.2 KiB
Plaintext
37 lines
1.2 KiB
Plaintext
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= Linked lists =
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A Sequential "list" of elements that is basically a daisy chain of pointers.
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Comes in single and double linked flavors. This thing really has one good
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property but that can be abused by linking it with other data structures (think
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LRUCache)
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== Good for ==
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* Data that is often swaped or deleted, done in O(1)
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== Bad for ==
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* Basically everything else
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== Optimize ==
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If memory is a real concern you can XOR the pointers to the next and prev items.
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To do this you need to xor the prev and next addresses, then when traversing
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xor the previous and the combined pointer. This really is only when youre
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worrying about like 4 bytes per node and either have tons of nodes or memory is
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precious and the time spent XORing is a valid tradeoff.
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== Visual ==
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{{{
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Head Tail
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---------------- --------- --------- --------- ----------------
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| Data | | Data | | Data | | Data | | Data |
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| prev* (NULL) | <= | prev* | <= | prev* | <= | prev* | <= | prev* |
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| next* | => | next* | => | next* | => | next* | => | next* (NULL) |
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---------------- --------- --------- --------- ----------------
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}}}
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[[algorithms]]
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