In computer science, a mergeable heap (also called a meldable heap) is an abstract data type, which is a heap supporting a merge operation.
Definition A mergeable heap supports the usual heap operations:
Make-Heap(), create an empty heap. Insert(H,x), insert an element x into the heap H. Min(H), return the minimum element, or Nil if no such element exists. Extract-Min(H), extract and return the minimum element, or Nil if no such element exists. And one more that distinguishes it:
Merge(H1,H2), combine the elements of H1 and H2 into a single heap.
Trivial implementation It is straightforward to implement a mergeable heap given a simple heap: Merge(H1,H2):
x ← Extract-Min(H2) while x ≠ Nil Insert(H1, x) x ← Extract-Min(H2) This can however be wasteful as each Extract-Min(H) and Insert(H,x) typically have to maintain the heap property.
More efficient implementations Examples of mergeable heap data structures include:
Binomial heap Fibonacci heap Leftist tree Pairing heap Skew heap A more complete list with performance comparisons can be found at Heap (data structure) § Comparison of theoretic bounds for variants. In most mergeable heap structures, merging is the fundamental operation on which others are based. Insertion is implemented by merging a new single-element heap with the existing heap. Deletion is implemented by merging the children of the deleted node.
See also Addressable heap
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