When you say that something is O(N) or O(N^2) or whatever, you are saying that as N changes then the resource in question (time or memory normally) changes with that relation to it. So if something is O(N) and N doubles, then the time taken doubles.
To be pedantic, that's not true. O(N) means that the growth is at most linear. O(N^2) means that the growth is at most quadratic. This means that any algorithm that is O(N) is also O(N log N) and O(N^2).
If you want to express that an algorithm is linear (and not worst case linear), the correct function is use is called Θ.
Note also that hash lookups are, worst case, Θ(N). There's always a chance that all hash keys map to the same value, resulting in a linear list that needs to be searched.
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|