Help me understand time complexity algorithms

[prime oxide]

I understand the first statement depends on how many n there is, as it will loop until n so O(n).

I understand the second one is just 1 process regardless of n so its O(1).

The third i am still not understanding but i assume since one loop is dependent on n, nested in another n that it will be o(n²)

However, i dont understand how to get for example 2n+1 for the calculations for the first one. I dont understand how the second one is 2. How do i calculate this? Thank you.

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[near ember]

Think about sums to calculate complexity.

For example, for the first one, you do $\sum_{i=1}^n c = nc = O(n)$, with $c$ the time constant for assignment.

[pine granite]

Yojda

[near ember]

Now, try to determine big O of the 3rd one.

However, i dont understand how to get for example 2n+1 for the calculations for the first one. I dont understand how the second one is 2. How do i calculate this?

[pine granite]

Yojda