Data Structures | Heap | Question 1
What is the time complexity of Build Heap operation?
(Build Heap is used to build a max(or min) binary heap from a given array. Build Heap is used in Heap Sort as a first step for sorting.)
(A)
O(nLogn)
(B)
O(n^2)
(C)
O(n)
(D)
O(logn)
Answer: (C)
Explanation:
Following is algorithm for building a Heap of an input array A.
BUILD-HEAP(A)
heapsize := size(A);
for i := floor(heapsize/2) downto 1
do HEAPIFY(A, i);
end for
END
Although the worst-case complexity looks like O(N log N), upper bound of time complexity is O(n). See following links for the proof of time complexity. Time Complexity of building a heap.
Hence Option(C) is the correct answer.
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Last Updated :
07 Nov, 2019
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