Re: STL Map uses hashing?
On May 30, 4:28 pm, ytrem...@nyx.nyx.net (Yannick Tremblay) wrote:
In article <MPG.22a85e2e38d3b341989...@news.sunsite.dk>,
Jerry Coffin <jcof...@taeus.com> wrote:
In article <4353ee37-4fa4-4bc0-924f-482523333e21
@u12g2000prd.googlegroups.com>, pvinodhku...@gmail.com says...
I am reading about hashing techniques. The map data structure
available in C++ STL uses hashing techniques?
No -- it uses a balanced tree of some sort (e.g. AVL or
red-black tree).
For information, this is because of requirements:
A STL map is required to have a worse case find() of O log(N).
Balanced trees give you that. Although hash maps are
typically faster than balanced tree on large amount of random
data, they do not guarantee a worse case scenario of O log(N).
I don't know about the "typically faster". Their average access
time is faster IF the hash function is good. Typically, I find
that it's not always that good (although the situation is
improving).
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