Exam 2

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10]

Problem X2.1.

[6 pts] Tabulate the values taken on by i, j, and k as the program fragment below executes.

j = 1

k = 1

for i in range(4):

    k = k + i * j

    j = i

`i`:		0,	1,	2,	3
`j`:	1,	0,	1,	2,	3
`k`:	1,	1,	1,	3,	9

Problem X2.2.

[6 pts] Convert the below to an equivalent if statement where not doesn't appear.

if not (a == b and b >= c):

if a != b or b < c:

Problem X2.3.

[8 pts] What is displayed when the below program is executed?

def run():

    a = 1

    y = 2

    b = process(a)

    c = process(b)

    print a, b, c

    print y



def process(x):

    y = x + 1

    x = x * 2

    print y

    return x



run()

2
3
1 2 4

Problem X2.4.

[10 pts] Complete the below function so that it returns the smallest positive number in its parameter list. For example, min_positives([5, 2, -1, 3]) should return 2. You can assume the list has at least one positive number, which will be less than 999.

def min_positives(nums):

def min_positives(nums):

    min = 1000

    for n in nums:

        if n > 0 and n < min:

            min = n

    return min

Problem X2.7.

[10 pts] The file words.txt is a file containing several lines with one English word on each line. Complete the below Python fragment so that it displays all six-letter words beginning with q.

dictionary = open('words.txt')

for line in dictionary:

    word = line.rstrip()

    if len(word) == 6 and word[0] == 'q':

        print word

Problem X2.8.

[8 pts] What is displayed when the below program is executed?

nums = [7, 9, 6, 7, 8]

map = {}

for i in range(5):

    n = nums[i]

    map[n] = i

for key in map:

    print key, 'to', map[key]

7 to 3
9 to 1
8 to 4
6 to 2

S	→	A `a` \| `b` A
A	→	`a` S \| A `b` \| `a`

Exam 2

Problem X2.1.

Problem X2.2.

Problem X2.3.

Problem X2.4.

Problem X2.5.

Problem X2.6.

Problem X2.7.

Problem X2.8.

Problem X2.9.

Problem X2.10.