34 lines
1.1 KiB
Markdown
34 lines
1.1 KiB
Markdown
This min-heap implementation is a pretty standard binomial heap.
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## Representation in memory
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A heap consists of one or more binomial trees, each with a different order `k`
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and `2^k` total nodes. This heap can contain `2^64 - 1` elements at most, which
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is far more than your memory can contain, but it's still fun to mention.
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A tree does not have its own memory structure; a node that's the root of a
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binomial tree is simply called the tree.
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Each node has the following layout:
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```c
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typedef struct vieter_heap_node {
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uint64_t key;
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void *data;
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struct vieter_heap_node *largest_order;
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union {
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struct vieter_heap_node *next_tree;
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struct vieter_heap_node *next_largest_order;
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} ptr;
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uint8_t order;
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} vieter_heap_node;
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```
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Each node has a pointer to its child with the largest order (if the node's
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order is `0`, this pointer will be NULL). Each non-root node has a pointer to
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its sibling with the next-highest order. These pointers allow the children of a
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binomial tree to be recombined into a new tree, once their root has been
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pop'ed.
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Roots point to the binomial tree in the heap with the next largest order.
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