How to find complexity of any algorithm ?

 Hi,

 

For Binary search algorithm best case complexity is O(1) Big oh of one this case arrive when searching element is in middle of array.

 

For Worst case complexity is  O(log n) Big oh of log in beasuce  in each iteration or in each recursive call the search gets reduced to half of the array.for n elements in the array,there are log n iteration or recursive calls.

 

For detail information refer following site:

 

https://www.geeksforgeeks.org/complexity-analysis-of-binary-search/