Date: Wednesday, September 26, 2010.
1-2. A list of students in a class can be represented either
as an array or as a
vector. Let us assume that one of the students decided to drop
the class; in this case, we need to delete this student's name
from our list.
- For each of the two representations, write pieces
of code for deleting a student with a given number from a list.
Trace both pieces of code on the example of a list which initially
consisted students A, B, F, and C, and we remove a student # 2 (i.e.,
student F) from this list. As a result, you should have a list
consisting of three students A, B, and C.
what are advantages and
disadvantages of using vectors instead of arrays?
3-5. When trying to program Fibonacci numbers, a student made two
mistakes: used multiplication instead of addition, and used a wrong
initial value n(1) = 2 instead of n(1) = 1.
As a result, he got a sequence
of numbers n(0), n(1), ..., for which n(0) = 1, n(1) = 2, and
n(i) = n(i-1) * n(i-2) for all other i > 0. Since the numbers are
unusual, it is not easy for a TA to check the correctness of
the student's code.
By comparing these two methods,
what can you say about the
advantages and disadvantages of recursive versus non-recursive
- To help your TA, write a
recursive method for computing this new sequence n(i).
Trace your method on the
example of computing n(4).
- Write an iterative method for computing
n(i) and trace it too.
6. In a 2-D array, let g[s][t] represent the grade of student s on
test t. Based on this input, we need to find the average grade of
- Write a method that, given a 2-D array g, returns
a 1-D array a[s] of average grades.
- For example, if student 0 has
grades 100 and 96, and student 1 had grades 80 and 84, then
the array of averages should contain a = (100 + 96) / 2 = 98 and
a = (80 + 84) / 2 = 82. Trace your method on this example.
7-8. A student is so happy with his straight A grades that she decides
to print them in a nice way.
Write a method that uses recursion to print the following
A A A
up to a row with n A's.
- First, describe an algorithm.
transform your algorithm into a code.
- Trace this code on
the example of n = 2.
9. What are advantages and disadvantages of using enumerated
types as opposed to a list of strings? Give