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NNTP-Posting-Date: Tue, 16 Aug 2011 18:22:18 -0500
Message-ID: <4E4AFBAA.6AD2@mindspring.com>
Date: Tue, 16 Aug 2011 19:22:18 -0400
From: pete <pfiland@mindspring.com>
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Subject: Re: selection-sort in C
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.c:9495

arnuld wrote:
 
> void selectionSort(char s[], int len)
> {
>   int i, idx;
>   char tmp;
>   for(i = 0; i != len; ++i)

That loop is too long.

To sort an array of (N) elements,
you only have to sort the first (N - 1) elements.

void selectionSort(char s[], int len)
{
    int i, idx;
    char tmp;
    
    for(i = 0; i != len - 1; ++i) {
        idx = findSmallest(s, i, len);
        tmp = s[i];
        s[i] = s[idx];
        s[idx] = tmp;
    }
}

>     {
>       idx = findSmallest(s, i, len);

>       tmp = s[i];
>       s[i] = s[idx];
>       s[idx] = tmp;
>     }
> }

For an array of (N) elements
you could decrease the number of swaps to less than (N),
and you could also lighten the load 
on the findSmallest() function.

void selectionSort(char s[], int len)
{
    int i, idx;
    char tmp;
    
    for(i = 0; i != len - 1; ++i) {
        idx = findSmallest(s, i + 1, len);
        if (s[i] > s[idx]) {
            tmp = s[i];
            s[i] = s[idx];
            s[idx] = tmp;
        }
    }
}

-- 
pete