Question

Suppose we have a binary heap of n elements and wish to insert n more elements(not necessarily one after other). What would be the total time required for this?

I think it’s theta (n logn) as one insertion takes logn.

Answer 1

Assuming we are given:

• priority queue implemented by standard binary heap H (implemented on array)
• n current size of heap

We have following insertion properties:

• W(n) = WorstCase(n) = Θ(lg n) (Theta). -> W(n)=Ω(lg n) and W(n)=O(lg n)
• A(n) = AverageCase(n) = Θ(lg n) (Theta). -> W(n)=Ω(lg n) and W(n)=O(lg n)
• B(n) = BestCase(n) = Θ(1) (Theta). -> W(n)=Ω(1) and W(n)=O(1)

So for every case, we have

• T(n) = Ω(1) and T(n) = O(lg n)

WorstCase is when, we insert new minimal value, so up-heap has to travel whole branch.

BestCase is when, for minimal-heap (heap with minimal on top) we insert BIG (biggest on updated branch) value (so up-heap stops immediately).

You’ve asked about series of n operations on heap containing already n elements,
it’s size will grow

from n to 2*n

what asymptotically is …

n=Θ(n)
2*n=Θ(n)

What simplifies our equations. (We don’t have to worry about growth of n , as it’s growth is by constant factor).

So, we have “for n insertions” of operation:

• Xi(n) = X_for_n_insertions(n)
  • Wi(n) = Θ(n lg n)
  • Ai(n) = Θ(n lg n)
  • Bi(n) = Θ(n)
• it implies, for “all case”:
  • Ti(n) = Ω(n) and Ti(n) = O(n lg n)

P.S. For displaying Theta Θ , Omega Ω symbols, you need to have UTF-8 installed/be compatible.