Finding out the time complexity of your code can help you develop better programs that run faster. Some functions are easy to analyze, but when you have loops, and recursion might get a little trickier when you have recursion. After reading this post, you are able to derive the time complexity of any code.
In general, you can determine the time complexity by analyzing the program’s statements (go line by line). However, you have to be mindful how are the statements arranged. Suppose they are inside a loop or have function calls or even recursion. All these factors affect the runtime of your code. Let’s see how to deal with these cases.
Source: How to find time complexity of an algorithm?, an article by Adrian Mejia.