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a question on O(n^2) and O(n)

alex lotel
Ranch Hand

Joined: Feb 01, 2008
Posts: 191
how do we count the loops thing??
Ulf Dittmer
Marshal

Joined: Mar 22, 2005
Posts: 39547
    
  27
That depends on the circumstances. Two nested loops could cause an algorithm to have O(n^2) complexity, but not necessarily so. Do you have an example of what you're wondering about?


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alex lotel
Ranch Hand

Joined: Feb 01, 2008
Posts: 191
can you shed some light on this
i was tought that if we have 2 loops one
inside the other
that its
O(n^2)

but apparently this is not
true
can youexpalin me more of it??
Ulf Dittmer
Marshal

Joined: Mar 22, 2005
Posts: 39547
    
  27
That depends on what the code is doing in the loop.

This loop describes an O(N^2) algorithm, because everything at line X is being executed N^2 times:

But the following case describes O(N) because the amount of work being done rises linearly with N:
 
It is sorta covered in the JavaRanch Style Guide.
 
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