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