Base Cases in Recursion

The Recursion Exit Strategy

1:00

What a base case is, why it is required, how the call stack unwinds, common base-case patterns, and the three mistakes that cause infinite recursion.

By the end, you can

Identify the base case and recursive case in a given recursive function.
Explain why a missing or unreachable base case causes a stack overflow.
Trace the call stack for a small recursive call (e.g. factorial(4)) — both the descent and the unwind.
State the three rules for safe recursion and identify which rule a broken function violates.
Recognize and apply the four common base-case patterns (zero/one, empty collection, single element, null node).
Explain why Fibonacci requires two base cases and name them.
Diagnose the three classic base-case mistakes in a code snippet.

Up next in Recursion, Paradigms & Algorithm Analysis