Complexity is the analysis of how the time and space requirements of an algorithm vary according to the size of the input. Use this tag for reviews where the "Big O" is a concern.
Computational complexity is the analysis of how the time and space requirements of an algorithm vary according to the size of the input.
A common metric of complexity is "Big O" notation, which gives an upper-bound estimate of the running time or required memory. Big O focuses only on the growth behavior, disregarding constant factors, since constant factors would be insignificant for sufficiently large inputs. (An algorithm that requires 7 n + 5 steps and an algorithm that requires 10 n steps are both considered O(n); both of those would be considered less complex than an algorithm requiring 2 n2 steps, which is O(n2).)
