2.5 O-Notation

The "O" is for order,as in "Binary search is O(logn);it takes on the order of logn steps to search an array of n items. "
The notation O (f(n)) means that once n gets large ,the running time is proportional to at most f(n), for example , O(n²) or O(nlogn).

Notation	Name	Example
O(1)	constant	array index
O(logn)	logarithmic	binary search
O(n)	linear	string comparison
O(nlogn)	nlogn	quick sort
O(n2)	quadratic	simple sorting methods
O(n3)	cubic	matrix multiplication
O(2n)	exponential	set partitioning