recursion and iteration

Introduce

recursive ： Method call itself ,

iteration ： Use the original value of the variable to get the new value

Advantages and disadvantages

	advantage	shortcoming
recursive	The code is simple , Good readability	It takes up a lot of space , It is easy to cause stack overflow , Time complexity
iteration	Low time and space complexity	Complex code , Poor readability , The code logic is complex

The relationship between the two

To some extent, the two can be transformed into each other

There must be iterations in recursion , There is not necessarily recursion in iterations ,