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Let $H$ be a max binary heap with $n$ elements (vertexes).

Pick a vertex $z$ in the heap with height of $k$ ($0<k<\lg n$)

To every element in the sub heap of $z$ we add the constant value $c > 0$.

We need to fix $H$ to be again a max heap, withour changing the value of the elements in the heap.

We need to do it with run time of $O(2^k \cdot \lg n)$.


I know that $MAX-HEAPIFY$ takes $O(\lg n)$ and $2^k$ is the number of leafs in a tree with hright of $k$.

But i dont realy have an idea for an algoritm.

Any directions?

Thanks.

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It seems like you can do it in $O(k\log{}n)$ time. Just compare vertex $z$ with its parent $p$. If $z$ has lesser value then we are done. Else swap $z$ with $p$ and heapify subtree rooted in $p$. The vertex $z$ will be raised no more than $k$ times and each raise takes $O(\log{}n)$

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  • $\begingroup$ Yes thanks, but, if i understood you correctly thats the previous sub question, which i have already did, i have to do it with the run time i showed above. $\endgroup$ – Alon Apr 15 at 23:59
  • $\begingroup$ $f \in O(k\log n) \implies f \in O(2^{k}\log n)$ So we can say that the presented algorithm runs in $O(2^{k}\log n)$ time. Does it solve your problem? $\endgroup$ – Vladislav Bezhentsev Apr 16 at 0:45

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