David Majnemer cb8757aca7 Fix std::make_heap's worst case time complexity
std::make_heap is currently implemented by iteratively applying a
siftup-type algorithm.  Since sift-up is O(ln n), this gives
std::make_heap a worst case time complexity of O(n ln n).

The C++ standard mandates that std::make_heap make no more than O(3n)
comparisons, this makes our std::make_heap out of spec.

Fix this by introducing an implementation of __sift_down and switch
std::make_heap to create the heap using it.
This gives std::make_heap linear time complexity in the worst case.

This fixes PR20161.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@213615 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-22 06:07:09 +00:00
2013-09-28 01:25:55 +00:00
Description
No description provided
15 MiB
Languages
C++ 98.1%
HTML 1.2%
Python 0.4%
CMake 0.2%