Recursive list sum
18-minute lesson · module-recursion-02
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Recursive list sum
18-minute lesson · module-recursion-02
- Sum a flat list recursively without a loop.
- Detect a sublist with `isinstance(item, list)`.
- Recurse into nested lists to sum numbers at any depth.
- Recognize the empty list as the natural base case.
Source attribution
Status: adapted
How to Think Like a Computer Scientist: Interactive Edition — source · Recursion / Calculating the Sum of a List of Numbers
Adaptation notes. Reading rewritten in our voice. We extend the chapter's flat-list sum to arbitrarily nested lists, which is the natural "recursion shines here" payoff. Hidden tests cover flat lists, deeply nested lists, and empties.
License notes. Original chapter is GNU FDL 1.3 (Brad Miller, David Ranum, and the upstream Elkner/Downey/Meyers text). No verbatim text reproduced.