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irbaboon

Sorting some numbers...kind of

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Hey


std::list <unsigned int> Numbers;
for (unsigned int i = 0; i < 100; i++) {
Numbers.push_back(rand() % 9500);
}


Okay, so we have that piece of code. Right?

What I want to do now is to output all those numbers from lowest to highest.
Like, (31, 52, 60, 79) and not (85, 20, 852, 521)

So now you may be thinking: "Oh, that's just to swap the numbers and sort them like that."

But the thing is, I don't want to swap the numbers inside the list...
I want to simply just get the lowest number in the list like...
OutputNumbersFromLowestToHighest(Numbers);

And then it'd give me the answer. And again, I don't want anything in the Numbers list to change, I just want it read.


Thanks in advance smile.png

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Pass the list to the function by value, or pass it by reference and make an internal copy of it, and then sort it. You get the values in order, and the list is unchanged.

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Thanks for your reply, but I think you misunderstood.
I don't want the indexes to change at all. I want to simply output the numbers directly in order.
Because, when I use the sorted list, the indexes aren't the same... Get me?
I need each index to have their specific number.
I have a feeling recursion might be useful for this, but I can't come up with anything.

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Why not make a sorted copy of the list using a set (or a map if you want to print its index as well as the values in order)?


L. Spiro

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1. I love your name. YogurtEmperor.

2. If I understand correctly, you mean I should basically have a 2D list?
So I could get the index and number. I guess that makes sense.

Thanks. If anyone has anything else to add, do tell smile.png

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Thanks for your reply, but I think you misunderstood.
I don't want the indexes to change at all. I want to simply output the numbers directly in order.
Because, when I use the sorted list, the indexes aren't the same... Get me?
I need each index to have their specific number.
I have a feeling recursion might be useful for this, but I can't come up with anything.

I still don't see how sorting a copy won't work. If all you want is to output the numbers in order, how can you not sort a copy of the list and output it? The values come out in order, and the list is unchanged. Those are the only two requirements I can find in your posts.

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[quote name='Segun24' timestamp='1329132415' post='4912549']
Thanks for your reply, but I think you misunderstood.
I don't want the indexes to change at all. I want to simply output the numbers directly in order.
Because, when I use the sorted list, the indexes aren't the same... Get me?
I need each index to have their specific number.
I have a feeling recursion might be useful for this, but I can't come up with anything.

I still don't see how sorting a copy won't work. If all you want is to output the numbers in order, how can you not sort a copy of the list and output it? The values come out in order, and the list is unchanged. Those are the only two requirements I can find in your posts.
[/quote]

He wants for instance:

[1, 6, 2, 4]

to be 'outputted' like:

[1 (index 0), 2 (index 2), 4 (index 3), 6 (index 1)]

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What about something like this:

int getNext(int n)
{
int candidate = inf;
foreach(value in list)
{
if(value <= n) continue;
if(value < candidate)
candidate = value;

}

return candidate;
}

And then:

int val = inf;
for(int i = 0; i < list.length(); ++i)
{

val = gentNext(val);
if(val == inf)
break; //no more numbers in list

print val;
}

Could most probably use some more work, but should work...

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2. If I understand correctly, you mean I should basically have a 2D list?
So I could get the index and number. I guess that makes sense.



No. 'copy list' != 'make 2D list'.

As two others already mentioned, the easiest way to solve this problem is to make a copy of the list, sort the copy (leaving the original unchanged), and print each item.

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