java - Big O Complexity for nested loop -

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for (i = 0; < 2*n; += 2)  {   (j=n; j > i; j--)     //some code yields o(1) }

i thought above yield n*log(n) i've seen source n^2 complexity big oh. please explain me , how approach problems in future.

since big o upper bound, n * n <= n^2, resulting in o(n*2). answer right


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