# big O complexity

 ragmar thomas · September 20, 2014 ``for(int i = 0; i < 1; i++) for(int j = 0; j < 1; j++) a = i;``what is the big O of this fragment code.i said it will be O(n2), but my teacher said it is O(n)``for(int i = 0; i < n*n; i++) for(int j = 0; j <= i; j++) a = i;``and for this one i said it is O(n3), but my teacher said  it is O(n2)is there any one who can help me understand that i am wrong, i can't admit it.I just did it in an assumption that all arithmetic and logical operations will be computed onces and for each nested loop there will be an extra n.

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 Franz Schmidt · September 20, 2014 You are right for each nested loop there would be an extra n, BUT:You say``a = i;``So the nested loop doesn't effect the a.You would be right if you do:``a++;`` ragmar thomas · September 22, 2014 no no with out the respect of``a = i;``that it possible that for every for loop whether ``for(int i = 0; i < 1; i++)``or``for(int i = 0; i < n; i++)``it will be counted as n, since it is true for the first case that is ``i = 0; and i < 1; or i < n;``this is true and for this matter it will be said n times so the complexity is  n.long story short i have heard and read that every loop whether for or while is counted as n times, if the first condition is true and the statement in it executed once or n times. hope 'm right.
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