O(1)
O(n)
O(n!)
n square -> O(n^2)
log(n) -> O(log(n))
n * log(n) -> O(nlog(n))
n + k -> O(n+k)
…

Please use the “short” notation (don’t use constants). Example: O(nk) or O(wn) should be written O(n). If an answer is required within a file, all your answers files must have a newline at the end.