# 4.13. Summary¶

In this chapter we have looked at examples of several recursive algorithms. These algorithms were chosen to expose you to several different problems where recursion is an effective problem-solving technique. The key points to remember from this chapter are as follows:

• All recursive algorithms must have a base case.

• A recursive algorithm must change its state and make progress toward the base case.

• A recursive algorithm must call itself (recursively).

• Recursion can take the place of iteration in some cases.

• Recursive algorithms often map very naturally to a formal expression of the problem you are trying to solve.

• Recursion is not always the answer. Sometimes a recursive solution may be more computationally expensive than an alternative algorithm.