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From: bigelow@hpfcso.HP.COM (Jim Bigelow)
Newsgroups: comp.lang.pascal
Subject: Re: [William Sweetman:  help - binary search tree]
Message-ID: <9110006@hpfcso.HP.COM>
Date: 1 Dec 89 16:14:46 GMT
References: <21597@adm.BRL.MIL>
Organization: Hewlett-Packard, Fort Collins, CO, USA
Lines: 25

I suggest that you look at the algorithms and programs in "Algorithms +
Data Structurs = Programs" by N. Wirth.  Chapter 4, Section 4.4 is titled
"Tree Structures"  and subsection 4.4.10 is "Optimal Search Trees."  

From the same book, Page 204, I've paraphrased the following search routine:

procedure search(x:integer; var p:ref);
begin
    if p = nil then
    begin
        { x not in tree, insert or inform user as you wish}
    end else 
    if x < p^.key then search(x,p^.left) else
    if x > p^.key then search*x,p^.right) else
        p^.count := p^.count + 1
end {search};

You'll have to modify the defintion and uses of "ref" which is a pointer to a 
tree node.

Best Regards,

Jim Bigelow
S300 Pascal
Hewlett Packard.