1
h13
CS8 S18
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Umail address: @umail.ucsb.edu
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h13: Perkovic 10.1 (Introduction to Recursion - up to Practice Problem 10.3)

ready? assigned due points
true Thu 05/10 03:30PM Thu 05/17 03:30PM

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.
There is NO MAKEUP for missed assignments, and you may not submit work in advance, or on behalf of another person.
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, if you MUST submit it on multiple sheets, JUST write your name at the top of both sheets and turn in both sheets UNCONNECTED.

    DO NOT staple, paper clip, spit-fold-and-tear, 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 checking the appropriate boxes. You might check only one of the two boxes, both boxes, or neither.

    Then determine what the output will be (if any) when the function is called as count(4). If no output is produced, check the “No output” option. If the execution never ends, check the “execution never ends” and write only the first three lines of output.

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