Quiz |
Posted (Thursdays) |
Given in class (Thursdays) |

| 21 | Sep |
28 | Sep |

### Information about quizzes:

- On the date a quiz is given, a die will be thrown by a student in
the class.
- Books and notes are put away.
- A question very similar to the chosen published question will be written
on the board.
- You have 5 minutes to answer the question.

The questions are intended to be straightforward. If you keep up with
the material in the class, almost no preparation may be necessary.
The Collaboration Policy allows you to
study
in groups for the quizzes, but you are on your own when you take the quiz.
You will fare better on the quiz if you
try working the problems before looking at
the solutions. If you don't understand the question or its answer,
please get help.

**Directions:**
Study the following recursive procedures and answer the
questions that follow. Do these practice exercises on paper. Do not
type them into a computer. You'll learn much more doing them by hand.

int factorial(int n) {
if (n <= 1)
return 1;
else
return (n * factorial(n-1));
}
int sum1toN(int n) {
if (n < 1)
return 0;
else
return (n + sum1toN(n-1));
}
int add(int i, int j) { // assumes i >= 0
if (i == 0)
return j;
else
add(i-1, j+1);
}
int fib(int n) { // assumes n >= 0
if (n <= 1)
return n;
else
return (fib(n-1) + fib(n-2));
}

- Identify the termination conditions (and resulting
base case return values) in each of the above recursive
procedures.
- Identify the recursive calls in each of the above
procedures.
- Using the substitution model, show all the
recursive calls and final result in the execution of
`factorial(5)`

.
For this same computation, draw the execution stack as it would
look just before returning from `factorial(1)`

,
the last recursive call.
- Using the substitution model, show all the
recursive calls and final result in the execution of
`sum1toN(5)`

.
- Using the data flow model, show all the
recursive calls and final result in the execution of
`add(5,9)`

.
For this same computation, draw the execution stack as it would
look just before returning from `add(0,14)`

,
the last recursive call.
- Using the data flow model, show all the
recursive calls and final result in the execution of
`fib(5)`

.

[ solution ]

Last modified 22:12:21 CST 31 January 1999
by Ron K. Cytron