Question

Data Structures and Algorithms Unit Test 12 of 2212 of 22 Items Question For the recursive factorial function output shown below, which lines of output would reflect the backward phase? 1 factorial(3) 2 3 * factorial(2) 3 3 * 2 * factorial(1) 4 3 * 2 * 1 5 3 * 2 6 6 (1 point) Responses 1,2,3,4,5,6 1,2,3,4,5,6 1,2,3 1,2,3 1,4 1,4 4,5,6 4,5,6 Skip to navigation page 1 of 1

Answer 1

To understand the output of the recursive factorial function and identify the backward phase, we can break down the output lines. The recursive definition of the factorial function generally follows this form:

• Base case: factorial(1) = 1
• Recursive case: factorial(n) = n * factorial(n-1)

Given Output Lines:

1. factorial(3) - Initial call (not part of backward phase)
2. 3 * factorial(2) - Recursion goes deeper (not part of backward phase)
3. 3 * 2 * factorial(1) - Recursion goes deeper (not part of backward phase)
4. 3 * 2 * 1 - This is the result of factorial(1) coming back up (start of backward phase)
5. 3 * 2 - This line results from the return of factorial(2), which is 2 (backward phase)
6. 6 - This is the final result of factorial(3) (backward phase)

Backward Phase Identification:

The backward phase is the part where the function resolves the recursive calls and returns values back up the call stack. Based on the output:

• Lines 4, 5, and 6 reflect the backward phase as they show the resolution of the recursive calls.

Conclusion:

The correct answer reflecting the backward phase is 4, 5, 6. So, the final answer would be:

4, 5, 6.