Mergeable heaps (also known as meldable heaps) are a class of heap that support an additional operation: merging two heaps into one.
We are considering a min mergeable heap. Alternatively, we could define a mergeable max heap with the operation MAXIMUM and EXTRACT-MAX.
The time complexity of the mergeable heaps' operations, including the additional merge operation, will depend on the type of heap used.
For example, if using Fibonacci heaps, merging complexity will be