1
h13
CS8 W18
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(as it would appear on official course roster)
Umail address: @umail.ucsb.edu
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if different from name above.
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h13: Perkovic 10.1 (Introduction to Recursion - up to Practice Problem 10.3)

ready? assigned due points
true Tue 03/06 02:00PM Tue 03/13 02:00PM

You may collaborate on this homework with AT MOST one person, an optional "homework buddy".

MAY ONLY BE TURNED IN IN THE LECTURE/LAB LISTED ABOVE AS THE DUE DATE,
OR IF APPLICABLE, SUBMITTED ON GRADESCOPE. There is NO MAKEUP for missed assignments;
in place of that, we drop the four lowest scores (if you have zeros, those are the four lowest scores).

READING ASSIGNMENT

Please read Perkovic 10.1 (Introduction to Recursion - up to Practice Problem 10.3). Then complete these problems and turn in your completed homework in lecture on the due date.

  1. (10 pts) Please fill in the information at the top of this homework sheet, including your name and umail address. If the other two items apply, please fill them in as well. Please do this every single time you submit homework for this class. It is important to fill in both name and umail every time, since handwriting is sometimes difficult to decipher. Having both helps us ensure you get credit for your work. Also: while we strongly prefer that you submit your homework on a single sheet of paper passed out in lecture, if you MUST submit it on multiple sheets, JUST write your name at the top of bot sheets and turn in both sheets UNCONNECTED. DO NOT staple, paper clip, fold, or do ANYTHING that would make it difficult to automatically feed your paper through a scanner.

  2. (10 pts) What is the significance of a “base case” in a recursive function?

  3. On page 332, the author talks about two important properties of recursive functions:

    • There exist one or more base cases which provide the stopping condition for the functions
    • One or more recursive calls on arguments that are “closer” to the base cases (progress to the base case)

    For each of the following implementations of count(n), indicate which of the two properties are satisfied by circling the appropriate option. Then write the output when the function is called as count(4). If no output is produced, circle the “No output” option. If the execution never ends, circle “execution never ends” and write the first four characters printed. You may circle multiple options as appropriate. Finally write if either there is no output or execution never ends (or both), explain why that happened in light of the recursive properties that the function did not satisfy

    1. (10 pts) 
      def count(n):
  print(n)
  count(n-1)
      		Base case(s) exist Progress to base case
      No output produced Execution never ends Output:
    2. (10 pts) 
      def count(n):
  count(n-1)
  print(n)
      		Base case(s) exist Progress to base case
      No output Execution never ends Output:
    3. (20 pts) 
      def count(n):
  if n < 0:
    return
  count(n-1)
  print(n)
      		Base case exists Progress to base case
      No output Execution never ends Output:
    4. (20 pts) 
      def count(n):
  if n <= 0:
    print("Blast off!")
    return
  print(n)
  count(n)
      		Base case exists Progress to base case
      No output produced Execution never ends Output:
    5. (20 pts) 
      def count(n):
  if n <= 0:
    return 0
  result = n + count(n-1)
  print(result)
  return result
      		Base case exists Progress to base case
      No output Execution never ends Output: