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Exercises > Build heap

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A heap can be built from a table of random keys by using a linear time bottom-up algorithm (a.k.a., Build-Heap, Fixheap, and Bottom-Up Heap Construction). This algorithm ensures that the heap-order property (the key at each node is lower than or equal to the keys at its children) is not violated in any node.

Algorithm 1 Build-Min-Heap(A)

for iheap-size[A]/2 - 1 downto 0 do
Min-Heapify (A, i)
end for

Algorithm 2 Min-Heapify(A, i)

if l < heap-size[A] and A[l] < A[i] then
end if
if r < heap-size[A] and A[r] < A[smallest] then
end if
if smallest ≠ i then
Min-Heapify(A, smallest)
end if

  Last modified Tue Mar 01 20:54:04 EET 2011