Time Complexity Analysis (Reference)
Maximum Complexity which can be handled by compiler will be O(10^6)
1. So in case of O(n) solution -> constraints will be n <= 10^6
2. In case of O(n^2) solution -> constraints will be n <= 10^3 as (10^3 * 10^3 == 10^6)
Similiarly with others-> all you have to do is just substitute the value of n in the worst case complexity!!