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author | Tim Peters <tim.peters@gmail.com> | 2002-08-03 02:11:26 (GMT) |
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committer | Tim Peters <tim.peters@gmail.com> | 2002-08-03 02:11:26 (GMT) |
commit | aa7d24319ebf62d38463e798b99be1afad314db6 (patch) | |
tree | f6d85602886e36efb809771caf43161d6bbcb0da /Lib/heapq.py | |
parent | 0e0a479821edf7e874fa13c69712448ca72ecc7e (diff) | |
download | cpython-aa7d24319ebf62d38463e798b99be1afad314db6.zip cpython-aa7d24319ebf62d38463e798b99be1afad314db6.tar.gz cpython-aa7d24319ebf62d38463e798b99be1afad314db6.tar.bz2 |
Minor fiddling, including a simple class to implement a heap iterator
in the test file. I have docs for heapq.heapify ready to check in, but
Jack appears to have left behind a stale lock in the Doc/lib directory.
Diffstat (limited to 'Lib/heapq.py')
-rw-r--r-- | Lib/heapq.py | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/Lib/heapq.py b/Lib/heapq.py index abdad03..dfda498 100644 --- a/Lib/heapq.py +++ b/Lib/heapq.py @@ -13,7 +13,7 @@ heap = [] # creates an empty heap heappush(heap, item) # pushes a new item on the heap item = heappop(heap) # pops the smallest item from the heap item = heap[0] # smallest item on the heap without popping it -heapify(heap) # transform list into a heap, in-place, in linear time +heapify(x) # transforms list into a heap, in-place, in linear time Our API differs from textbook heap algorithms as follows: @@ -175,16 +175,16 @@ def heappop(heap): returnitem = lastelt return returnitem -def heapify(heap): - """Transform list heap into a heap, in-place, in O(len(heap)) time.""" - n = len(heap) +def heapify(x): + """Transform list into a heap, in-place, in O(len(heap)) time.""" + n = len(x) # Transform bottom-up. The largest index there's any point to looking at # is the largest with a child index in-range, so must have 2*i + 1 < n, # or i < (n-1)/2. If n is even = 2*j, this is (2*j-1)/2 = j-1/2 so # j-1 is the largest, which is n//2 - 1. If n is odd = 2*j+1, this is # (2*j+1-1)/2 = j so j-1 is the largest, and that's again n//2-1. for i in xrange(n//2 - 1, -1, -1): - _siftdown(heap, i) + _siftdown(x, i) if __name__ == "__main__": # Simple sanity test |