The importance of these notations
It usually doesn’t matter how a program performs on small inputs
For large inputs, these notations show what dominates performance
Practical calibration, for input size n:
- O(1): Ideal, but usually impossible
- O(n): Usually the best possible, often unattainable
- O(n log n): Almost as good as O(n)
- O(n2): OK in toy programs but not for serious purposes
- O(n3): Hopeless even for toy programs