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java lists

Posted on 2004-09-29
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Last Modified: 2010-04-17
how can I find the second highest value in a list of integers? and also the second lowest ?
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Question by:rwallacej
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Assisted Solution

by:djspinnet
djspinnet earned 200 total points
ID: 12179369
to find the second highest,

declare two variables max and second_max

1) traverse the list
2) store the first integer in max
3) if the next int (let's call it x) is larger than max, assign second_max = max; and max = x;
4) continue traversing the whole list and performing the same operation
5) return second_low

same goes for second lowest, just change >= to <=
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csaba_b earned 300 total points
ID: 12180266
Hi djspinnet!
your solution won't work for the following list: 2, 1 ... sorry

my proposal is:

suppose the list contains at leas 2 members and in case when two members has the highest value, the second highest equals the highest :)

int max = ((Integer)list.next()).intValue();
int max2 = ((Integer)list.next()).intValue();
int mxc = max2;
while(true) {
  if(mxc>=max) {
    mx2 = max;
    max = mxc;
  } else if(mxc>max2) {
    max2 = mxc;
  }
  if(!list.hasNextt()) {
    break;
  }
  mxc = ((Integer)list.next()).intValue();
}

for the second lowest you just replace > with <

csaba
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Expert Comment

by:MogalManic
ID: 12180827
If speed is not an issue, just sort the list and grab the 2nd and 2nd from last item from the list
        Collections.sort(l);
        small=l.get(1);
        large=l.get(l.size()-2);
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Expert Comment

by:djspinnet
ID: 12188464
actually, my solution did work - i implemented it once ;)
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Expert Comment

by:csaba_b
ID: 12402861
To djspinnet:

Have you tried your algorithm with the list I mentioned? If yes, and the result was correct. you can accept the points offered.

I don't think so ...

Csaba
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