# Big O notation / algebraic formula

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### #1 rick2993

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# Big O notation / algebraic formula

Posted 01 February 2013 - 05:05 PM

Hey everyone. I can't seem to figure out the big O notation or the algebraic formula as it applies to this snippet of code.

I'm assuming it is O(n^2)?

Can anyone confirm this or help me out with the algebraic forumla?
e.g. N^2 + 3n

```for ( outerLoop = n - 1; outerLoop >= 0; outLoop++)
{
for (innerLoop = 0; innerLoop < outerLoop; innerLoop++)
{
{
}
}
}

```

ahhh sorry about the looks of the code. idk how to edit so here it is w/ indents

```for ( outerLoop = n - 1; outerLoop >= 0; outLoop++)
{
for (innerLoop = 0; innerLoop < outerLoop; innerLoop++)
{
{
}
}
}

```

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## Replies To: Big O notation / algebraic formula

### #2 macosxnerd101

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## Re: Big O notation / algebraic formula

Posted 01 February 2013 - 05:18 PM

There are n steps, so the series is equivalent to n(n+1)/2. There are three steps in the inner loop, so multiply by 3. So T(n) = 3/2 (n^2 + n), which is O(n^2).

### #3 rick2993

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• Posts: 3
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## Re: Big O notation / algebraic formula

Posted 01 February 2013 - 05:22 PM

Thanks you!

### #4 macosxnerd101

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## Re: Big O notation / algebraic formula

Posted 01 February 2013 - 05:23 PM