Subj : Re: resolving a list of numbers to a range
To   : comp.programming
From : rossum
Date : Sat Aug 20 2005 12:06 am

On Thu, 18 Aug 2005 09:26:41 GMT, Randy Howard
<randyhoward@FOOverizonBAR.net> wrote:

>Espen Suenson wrote
>(in article <Pine.LNX.4.61.0508181040050.15328@tyr.diku.dk>):
>
>> placid wrote:
>> 
>>> Hi all,
>>> 
>>> I was just if anyone knows a way to resolve a list of integers say
>>> {1,2,3,4,5} into a range that is 1-5?
>> 
>> Here's an algorithm:
>> 
>> 1) Find the smallest integer in the list, this is A.
>> 2) Find the largest integer in the list, this is B.
>> 3) Return the range A-B.
>> 
>> One way of doing steps 1 and 2 is to sort the list. Then the smallest 
>> integer will be the first element and the largest integer will be the last 
>> element in the list.
>
>"It depends", and I know I'm going to regret posting this when 
>short on sleep and not knowing how "list" is stored, but you 
>might find that simply walking through the list, with two 
>variables, such as this pseudo-example is faster than sorting 
>it...
>
>low_end  = BIGGEST_VALUE_POSSIBLE;
>high_end = SMALLEST_VALUE_POSSIBLE;
Minor point:
 <check that list[0] exists>
 low_end = list[0];
 high_end = list[0];
 index = 1;
>
>while (!end_of_list(list, index))
>{
>   if (list[index].value < low_end)
>       low_end = list[index].value;
>   if (list[index].value > high_end)
>       high_end = list[index].value;
>   index++;
>}
>
>assert(low_end < high_end);
>
>return range(low_end, high_end);


rossum


The ultimate truth is that there is no ultimate truth

.