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<b>Data Structures and Algorithms 
with Object-Oriented Design Patterns in C++</b><br>
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<H3><A NAME="SECTION008214000000000000000">Removing Items from a List</A></H3>
<P>
The purpose of the <tt>Withdraw</tt> function is to remove
an item from the sorted list.
Program&nbsp;<A HREF="page193.html#progsorted4c" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/page193.html#progsorted4c"><IMG  ALIGN=BOTTOM ALT="gif" SRC="cross_ref_motif.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/icons/cross_ref_motif.gif"></A> defines the <tt>Withdraw</tt>
function which takes a reference to an <tt>Object</tt>.
<P>
<P><A NAME="11055">&#160;</A><A NAME="progsorted4c">&#160;</A> <IMG WIDTH=575 HEIGHT=277 ALIGN=BOTTOM ALT="program10810" SRC="img858.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img858.gif"  ><BR>
<STRONG>Program:</STRONG> <tt>SortedListAsArray</tt> Class 	<tt>Withdraw</tt> Member Function Definition<BR>
<P>
<P>
The <tt>Withdraw</tt> function makes use of <tt>FindOffset</tt>
to determine the array index of the item to be removed.
Removing an object from position <I>i</I> of 
an ordered list which is stored in an array
requires that all of the objects at positions
<I>i</I>+1, <I>i</I>+2, ...,  <IMG WIDTH=68 HEIGHT=20 ALIGN=MIDDLE ALT="tex2html_wrap_inline61316" SRC="img711.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img711.gif"  >,
be moved one position to the left.
The worst case is when <I>i</I>=0.
In this case,  <IMG WIDTH=68 HEIGHT=20 ALIGN=MIDDLE ALT="tex2html_wrap_inline61316" SRC="img711.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img711.gif"  > items need to be moved to the left.
<P>
Although the <tt>Withdraw</tt> function is able to make
use of <tt>FindOffset</tt> to locate the position
of the item to be removed in  <IMG WIDTH=56 HEIGHT=24 ALIGN=MIDDLE ALT="tex2html_wrap_inline59891" SRC="img403.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img403.gif"  > time,
the total running time is dominated by the left shift,
which is <I>O</I>(<I>n</I>) in the worst case.
Therefore, the running time of <tt>Withdraw</tt> is <I>O</I>(<I>n</I>).
<P>
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