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+1 vote
Why space complexity of heapsort is O(1)....and why not O(logn)..because of space required by recursion calls which is equivalent to height of the tree...where am i getting wrong plz help...
asked in Algorithms by (259 points)   | 272 views
I think auxillary space required will be O(1) but no total space complexity,not sure.

2 Answers

+1 vote

HEAP SORT uses MAX_HEAPIFY function which calls itself but it can be made using a simple while loop and thus making it an iterative function which inturn takes no space and hence Space Complexity of HEAP SORT can be reduced to O(1).

while ( i < = heapsize) {
 lc <- left(i)
 rc <- right(i)
 if (lc<=heapsize) and (A[lc]>A[i])
  largest <- lc
  largest <- i 
 if (rc<=heapsize) and (A[rc]>A[largest])
  largest <- rc
 if (largest != i)
   exchange A[i] <-> A[largest]
   i <- largest
answered by (201 points)  
yes, i am agree with the kamal.

since, recursive algorithm can be implemented using loops thats why we dont consider stack in  space complexity of the algoritm thats why O(1)
0 votes
answered by Boss (5.5k points)  
I have already seen this answer. But I am still not getting why space required by recursion calls is not considered.
very nice question. i have the same doubt.. It should be log n because every time we are calling  heapify on the root of tree?  experts advice needed...............

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