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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="SECTION0016511000000000000000">Implementation</A></H3>
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Program <A HREF="page503.html#progsorter7c" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/page503.html#progsorter7c"><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>StraightSelectionSorter<T></tt> class.
This class is derived from the abstract <tt>Sorter<T></tt> base class
and it provides an implementation for <tt>DoSort</tt>.
The <tt>DoSort</tt> routine follows directly from the algorithm discussed above.
In each iteration of the main loop (lines 11-18),
exactly one element is selected from the unsorted elements
and moved into the correct position.
A linear search of the unsorted elements is done in order
to determine the position of the largest remaining element (lines 14-16).
That element is then moved into the correct position (line 17).
<P>
<P><A NAME="39409"> </A><A NAME="progsorter7c"> </A> <IMG WIDTH=575 HEIGHT=371 ALIGN=BOTTOM ALT="program39246" SRC="img2184.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img2184.gif" ><BR>
<STRONG>Program:</STRONG> <tt>StraightSelectionSorter<T></tt> Class <tt>DoSort</tt> Member Function Definition<BR>
<P>
<P>
In all <I>n</I>-1 iterations of the outer loop are needed to sort the array.
Notice that exactly one swap is done in each iteration of the outer loop.
Therefore, <I>n</I>-1 data exchanges are needed to sort the list.
<P>
Furthermore, in the <IMG WIDTH=17 HEIGHT=13 ALIGN=BOTTOM ALT="tex2html_wrap_inline58387" SRC="img77.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img77.gif" > iteration of the outer loop,
<I>i</I>-1 iterations of the inner loop are required
and each iteration of the inner loop does one data comparison.
Therefore, <IMG WIDTH=40 HEIGHT=25 ALIGN=MIDDLE ALT="tex2html_wrap_inline59179" SRC="img261.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img261.gif" > data comparisons are needed to sort the list.
<P>
The total running time of the straight selection
<tt>DoSort</tt> routine is <IMG WIDTH=40 HEIGHT=25 ALIGN=MIDDLE ALT="tex2html_wrap_inline59179" SRC="img261.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img261.gif" >.
Because the same number of comparisons and swaps are always done,
this running time bound applies in all cases.
I.e., the best-case, average-case and worst-case
running times are all <IMG WIDTH=40 HEIGHT=25 ALIGN=MIDDLE ALT="tex2html_wrap_inline59179" SRC="img261.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img261.gif" >.
<P>
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