Question

Instructions

Lee has discovered what he thinks is a clever recursive strategy for printing the elements in a sequence (string, tuple, or list). He reasons that he can get at the first element in a sequence using the 0 index, and he can obtain a sequence of the rest of the elements by slicing from index 1. This strategy is realized in a function that expects just the sequence as an argument. If the sequence is not empty, the first element in the sequence is printed and then a recursive call is executed. On each recursive call, the sequence argument is sliced using the range 1:. Here is Lee’s function definition:


def printAll(seq):

if seq:

print(seq[0])

printAll(seq[1:])

Write a program that tests this function and add code to trace the argument on each call. Does this function work as expected? If so, are there any hidden costs in running it?


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Answer 1

The provided function printAll uses recursion to print all elements in a given sequence. It starts by checking if the sequence is not empty. If it is not empty, it prints the first element and makes a recursive call to printAll with the remaining elements (sliced from index 1).

To test this function and trace the argument on each call, you can add a print statement before the recursive call to display the current sequence. Here's an example program that demonstrates this:



When you run this program, it will print each element in the sequence along with the current sequence at each recursive call. This can help you trace the argument and understand how the function works.

The function should work as expected and print all elements in the sequence. However, there are potential hidden costs in running it. Recursive functions can consume a large amount of memory if the sequence is very long, as each recursive call adds a new stack frame to the call stack. This can lead to stack overflow errors or slow down the program's execution. In some cases, using a loop or an iterative approach may be more efficient and less prone to such issues.