CSP2 Quiz 1

Predict the output:

x = 7
x -= 2
if x % 2 == 0:
    print("even")
else:
    print("odd")

if x > 4:
    print("big")
elif x == 4:
    print("mid")
else:
    print("small")
print(x)

odd
big
5

Predict the output:

i = 2
total = 0
while i < 12:
    if i % 3 == 0:
        total += i
    i += 2
print(total)

6

Predict the output:

def describe(a, b):
    if a > b:
        print(a, "is greater")
    elif a < b:
        print(b, "is greater")
    else:
        print("equal")
    print("checked:", a, b)

describe(3, 8)
describe(10, 10)
x = 5
y = 2
describe(y, x)

8 is greater
checked: 3 8
equal
checked: 10 10
5 is greater
checked: 2 5

Predict the output:

words = ["cat", "dog", "owl"]
result = ""
for w in words:
    if len(w) == 3:
        result += w.upper()
    else:
        result += w
    result += "-"
print(result)
print(len(result))

CAT-DOG-OWL-
12

Predict the output:

for i in range(1, 4):
    for j in range(1, 3):
        if (i + j) % 2 == 0:
            print(i, j, "even")
print("done")

1 1 even
2 2 even
3 1 even
done

Find the errors, then fix this code:

def square(n)
    result = n * n
    return result

value = square(5)
if value = 25
print("perfect")
else:
print(value)

Errors:

• Missing colon after def square(n)
• Used = instead of == in the if statement
• Missing colon after if value == 25
• print("perfect") and print(value) are not indented

Fixed:

def square(n):
    result = n * n
    return result

value = square(5)
if value == 25:
    print("perfect")
else:
    print(value)

This code runs without crashing but gives the wrong answer — identify why and how to fix it:

def average(numbers):
    total = 0
    for n in numbers:
        total = n
    return total / len(numbers)

scores = [10, 20, 30, 40]
print(average(scores))

Bug: total = n overwrites total each loop instead of accumulating the sum, returning the last number divided by count (40 / 4 = 10.0).

Fix: Change total = n to total += n.

Corrected Output: 25.0

Find and fix the syntax error and logic error (goal: calculate and print N factorial):

number = int(input("Enter a positive integer: "))
product = 0
i = 1
while i <= number
    product = product * i
    i = i + 1
print("The factorial is:", product)

Errors:

• Missing colon after while i <= number
• product starts at 0, so every multiplication results in 0 (should start at 1)

Fixed:

number = int(input("Enter a positive integer: "))
product = 1
i = 1
while i <= number:
    product = product * i
    i = i + 1
print("The factorial is:", product)

Write Python code that asks the user for a number and prints "positive", "negative", or "zero" depending on the value.

number = float(input("Enter a number: "))
if number > 0:
    print("positive")
elif number < 0:
    print("negative")
else:
    print("zero")

Write a function count_vowels(word) that returns the number of vowels (a, e, i, o, u) in the string.

def count_vowels(word):
    count = 0
    for letter in word.lower():
        if letter in "aeiou":
            count += 1
    return count

Write code using a loop that prints the first 10 multiples of 4, one per line.

for i in range(1, 11):
    print(i * 4)

Write a function is_palindrome(s) that returns True if s reads the same forwards and backwards, False otherwise.

def is_palindrome(s):
    return s == s[::-1]

Predict the output:

nums = [3, 8, 2, 5]
total = 0
for n in nums:
    if n > 4:
        total += n
print(total)

13

Identify and fix the logic error in this function intended to find the maximum number in a list:

def find_max(numbers):
    max_val = numbers[0]
    for i in range(len(numbers)):
        if numbers[i] < max_val:
            max_val = numbers[i]
    return max_val

Bug: The comparison < finds the minimum instead of the maximum.

Fix: Change < to >.

def find_max(numbers):
    max_val = numbers[0]
    for i in range(len(numbers)):
        if numbers[i] > max_val:
            max_val = numbers[i]
    return max_val

Write a function reverse_string(text) that takes a string and returns it reversed using a loop.

def reverse_string(text):
    reversed_text = ""
    for char in text:
        reversed_text = char + reversed_text
    return reversed_text

Predict the output:

data = [1, 2, 3, 4, 5]
res = [x * 2 for x in data if x % 2 != 0]
print(res)

[2, 6, 10]

Predict the output:

counts = {}
for char in "banana":
    counts[char] = counts.get(char, 0) + 1
print(counts["a"])
print(counts["n"])

3
2

Identify and fix the syntax error in this code intended to check if a number is even:

def is_even(num):
    if num % 2 = 0:
        return True
    else:
        return False

Bug: Uses the assignment operator = instead of the equality comparison operator == inside the if condition.

Fix: Change = to ==.

def is_even(num):
    if num % 2 == 0:
        return True
    else:
        return False

Write a function sum_list(numbers) that returns the sum of all elements in a list using a loop (without using the built-in sum() function).

def sum_list(numbers):
    total = 0
    for num in numbers:
        total += num
    return total

Write a function find_smallest(numbers) that returns the smallest number in a list of numbers.

def find_smallest(numbers):
    smallest = numbers[0]
    for n in numbers:
        if n < smallest:
            smallest = n
    return smallest

Predict the output:

a = [1, 2, 3]
b = a
b.append(4)
print(len(a))

4

Predict the output:

def add_item(item, lst=[]):
    lst.append(item)
    return lst

print(add_item(1))
print(add_item(2))

[1]
[1, 2]

Predict the output:

x = 10
def func():
    x = 5
    print(x, end=" ")

func()
print(x)

5 10

Predict the output:

s = "python"
print(s[1:4])

yth

Predict the output:

vals = [10, 20, 30]
print(vals[-1])

30

Predict the output:

total = 0
for i in range(5):
    if i == 3:
        break
    total += i
print(total)

3

Predict the output:

total = 0
for i in range(5):
    if i == 2:
        continue
    total += i
print(total)

8

Predict the output:

d = {"a": 1, "b": 2}
print(d.get("c", 3))

3

Predict the output:

pairs = [(1, 'a'), (2, 'b')]
for num, char in pairs:
    print(char, num)

a 1
b 2

Predict the output:

x = "10"
y = "20"
print(x + y)

1020

Predict the output:

nums = [1, 2, 3, 4]
print(nums[::-1])

[4, 3, 2, 1]

Predict the output:

def mult(a, b=2):
    return a * b

print(mult(4))
print(mult(4, 3))

8
12

Write a function factorial(n) using recursion that returns the factorial of n.

def factorial(n):
    if n <= 1:
        return 1
    return n * factorial(n - 1)

Write a function remove_duplicates(lst) that returns a new list with unique elements preserved in order.

def remove_duplicates(lst):
    result = []
    for item in lst:
        if item not in result:
            result.append(item)
    return result

Write a function flatten(nested_list) that takes a list of lists and returns a single flat list.

def flatten(nested_list):
    flat = []
    for sublist in nested_list:
        for item in sublist:
            flat.append(item)
    return flat

Write code using list comprehension to create a list of square numbers for integers from 1 to 5.

squares = [x**2 for x in range(1, 6)]

Write a function is_even(n) that returns True if n is even and False otherwise.

def is_even(n):
    return n % 2 == 0

Write a function max_of_three(a, b, c) that returns the largest of three numbers without using max().

def max_of_three(a, b, c):
    if a >= b and a >= c:
        return a
    elif b >= a and b >= c:
        return b
    else:
        return c

Identify and fix the bug in this function intended to return the average of a list:

def calc_avg(nums):
    return sum(nums) / len(nums)

print(calc_avg([]))

Bug: Passing an empty list causes a ZeroDivisionError because len(nums) is 0.

Fix: Check if the list is empty before dividing.

def calc_avg(nums):
    if not nums:
        return 0
    return sum(nums) / len(nums)

Identify and fix the error in this code:

age = input("Enter your age: ")
if age >= 18:
    print("Adult")

Bug: input() returns a string, so comparing age >= 18 causes a TypeError.

Fix: Convert input to an integer int(input("...")).

age = int(input("Enter your age: "))
if age >= 18:
    print("Adult")

Predict the output:

print(bool(""))
print(bool("Hello"))
print(bool(0))
print(bool([1]))

False
True
False
True

Predict the output:

names = ["Alice", "Bob", "Charlie"]
for i, name in enumerate(names):
    print(i, name)

0 Alice
1 Bob
2 Charlie

Predict the output:

a = [1, 2, 3]
b = [4, 5, 6]
print(list(zip(a, b)))

[(1, 4), (2, 5), (3, 6)]

Write a function count_occurrences(lst, item) that counts how many times item appears in lst.

def count_occurrences(lst, item):
    count = 0
    for x in lst:
        if x == item:
            count += 1
    return count

Write a function celsius_to_fahrenheit(c) that converts Celsius to Fahrenheit using formula $F = C \times \frac{9}{5} + 32$.

def celsius_to_fahrenheit(c):
    return c * (9 / 5) + 32

Predict the output:

text = "hello world"
print(text.title())
print(text.split())

Hello World
['hello', 'world']

Predict the output:

x = 5
y = 10
x, y = y, x
print(x, y)

10 5

Identify and fix the issue in this code intended to mutate a tuple:

tup = (1, 2, 3)
tup[0] = 99
print(tup)

Bug: Tuples are immutable in Python, so assigning to tup[0] raises a TypeError.

Fix: Convert tuple to a list first if mutation is needed, or reassign a new tuple.

lst = list(tup)
lst[0] = 99
tup = tuple(lst)
print(tup)

Write a function is_prime(n) that returns True if n is a prime number (greater than 1) and False otherwise.

def is_prime(n):
    if n <= 1:
        return False
    for i in range(2, int(n ** 0.5) + 1):
        if n % i == 0:
            return False
    return True

Write a function merge_dicts(d1, d2) that combines two dictionaries, with values from d2 overwriting d1 on key collisions.

def merge_dicts(d1, d2):
    merged = d1.copy()
    merged.update(d2)
    return merged