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

[alex lotel]

how do we count the loops thing??

[Ulf Dittmer]

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?

[alex lotel]

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]

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:

int N = 100;
 
for (int i=0; i<N; i++) {
   for (int j=0; j<N; i++) {
      // X
   }
}

But the following case describes O(N) because the amount of work being done rises linearly with N:

for (int i=0; i<N; i++) {
   for (int j=0; j<100; i++) {
      // X
   }
}