Python Online Test

A megastore offers three types of discounts, which are represented as DiscountType enum.

Implement the get_discounted_price function which should take the total weight of the shopping cart, the total price, and the discount type. It should return the final discounted price based on the discount schemes as shown in the promotional video below:

(Open full-size video in a new tab)

For example, the following code:

print(get_discounted_price(12, 100, DiscountType.WEIGHT))

should print:

82.0

A turn-based strategy game has a grid with water and land. The grid contains a True value where it's water and False where it's land.

The player controls a boat unit with a particular movement pattern. It can only move to fixed destinations from its current position as shown in the video below:

The boat can only move in a direct path through water to the possible destinations, so a destination will become unreachable if there is land in the way.

Implement the can_travel_to function, that checks whether a destination is reachable by the boat. It should return True for destinations that are reachable according to the pattern above, and False for unreachable or out of bounds destinations which are outside the grid.

For example, consider the following code:

game_matrix = [
    [False, True,  True,  False, False, False],
    [True,  True,  True,  False, False, False],
    [True,  True,  True,  True,  True,  True],
    [False, True,  True,  False, True,  True],
    [False, True,  True,  True,  False, True],
    [False, False, False, False, False, False],
]

print(can_travel_to(game_matrix, 3, 2, 2, 2)) # True, Valid move
print(can_travel_to(game_matrix, 3, 2, 3, 4)) # False, Can't travel through land
print(can_travel_to(game_matrix, 3, 2, 6, 2)) # False, Out of bounds

The following image shows valid and invalid destinations when the boat is in the position (3, 2):

A gaming company is working on a platformer game. They need a function that will compute the character's final speed, given a map and a starting speed.

The terrain on which the game character moves forward is made from various pieces of land placed together. Implement the function calculate_final_speed which takes the initial speed of the character, and a list of degrees of inclination that represent the uneven terrain.

The speed of the character will increase or decrease proportionally to the incline of the land, as shown in the image below:

The magnitude of the angle of inclination will always be < 90°. The speed change occurs only once for each piece of land. The function should immediately return 0 as the final speed if an incline reduces the speed to 0 or below 0, which makes the character lose 1 life.

For example, the below code:

print(calculate_final_speed(60, [0, 30, 0, -45, 0]))

should print:

75

A user interface contains two types of user input controls: TextInput, which accepts all characters and NumericInput, which accepts only digits.

Implement the class TextInput that contains:

• Method add(self, character) - adds the given character to the current value
• Method get_value(self) - returns the current value

Implement the class NumericInput that:

• Inherits TextInput
• Overrides the add method so that each non-numeric character is ignored

For example, the following code should output "10":

input = NumericInput()
input.add("1")
input.add("a")
input.add("0")
print(input.get_value())

Implement function count_numbers that accepts a sorted list of unique integers and, efficiently with respect to time used, counts the number of list elements that are less than the parameter less_than.

For example, count_numbers([1, 3, 5, 7], 4) should return 2 because there are two list elements less than 4.

As part of a data processing pipeline, complete the implementation of the pipeline method:

• The pipeline method should accept a variable number of functions, and it should return a new function that accepts one parameter arg.
• The returned function should call the first function in pipeline with the parameter arg, and call the second function with the result of the first function.
• The returned function should continue calling each function in pipeline in order, following the same pattern, and return the value from the last function.

For example, calling pipeline(lambda x: x * 3, lambda x: x + 1, lambda x: x / 2), and then calling the returned function with 3 should return 5.0.

A playlist is considered a repeating playlist if any of the songs contain a reference to a previous song in the playlist. Otherwise, the playlist will end with the last song which points to None.

Implement a function is_in_repeating_playlist that, efficiently with respect to time used, returns true if a playlist is repeating or false if it is not.

For example, the following code prints "True" as both songs point to each other.

first = Song("Hello")
second = Song("Eye of the tiger")
    
first.next_song(second)
second.next_song(first)
    
print(first.is_in_repeating_playlist())

The LeagueTable class tracks the score of each player in a league. After each game, the player records their score with the record_result function. 

The player's rank in the league is calculated using the following logic:

1. The player with the highest score is ranked first (rank 1). The player with the lowest score is ranked last.
2. If two players are tied on score, then the player who has played the fewest games is ranked higher.
3. If two players are tied on score and number of games played, then the player who was first in the list of players is ranked higher.

Implement the player_rank function that returns the player at the given rank.

For example:

table = LeagueTable(['Mike', 'Chris', 'Arnold'])
table.record_result('Mike', 2)
table.record_result('Mike', 3)
table.record_result('Arnold', 5)
table.record_result('Chris', 5)
print(table.player_rank(1))

All players have the same score. However, Arnold and Chris have played fewer games than Mike, and as Chris is before Arnold in the list of players, he is ranked first. Therefore, the code above should display "Chris".

Implement a group_by_owners function that:

• Accepts a dictionary containing the file owner name for each file name.
• Returns a dictionary containing a list of file names for each owner name, in any order.

For example, for dictionary {'Input.txt': 'Randy', 'Code.py': 'Stan', 'Output.txt': 'Randy'} the group_by_owners function should return {'Randy': ['Input.txt', 'Output.txt'], 'Stan': ['Code.py']}.

The Python function get_system_info returns the config settings for the app. The code below shows the function in use:

import platform

def get_system_info(detailed):
    if detailed:
        return {
            "platform": "Linux",
            "language": platform.python_branch(),
            "userAgent": platform.platform()
        }

    return "Linux"

info = get_system_info(False)
print(info["platform"])

The code causes the following runtime error:

TypeError: string indices must be integers, not 'str'

Explain in short why the error occurred.

(An answer up to 40 words is sufficient)

You are working on a calculator application where users can input a mathematical expression such as: (3 + 5) * (2 - 4).

To correctly evaluate this expression, the application needs to validate the expression and ensure that the parentheses are balanced. The balanced parentheses are crucial for determining the order of operations and evaluating the expression correctly.

You have used an AI assistant to generate the following static function to check if the parentheses in an expression are balanced:

def is_balanced(parentheses):
    stack = []
    opening = set({'(', '[', '{'})
    closing = set({')', ']', '}'})
    pairs = dict({
        ')': '(',
        ']': '[',
        '}': '{'
    })

    for c in parentheses:
        if c in opening:
            stack.append(c)
        elif c in closing:
            if not stack or stack[-1] != pairs[c]:
                return False
            stack.pop()

    return len(stack) == 0

What are correct statements for the given function?

A university's Office of Admission keeps track of student majors. Each student can have a single major. Below is an example of how their system stores students and majors, and how it manipulates them:

students = [("Allen Anderson", "Computer Science"),
            ("Edgar Einstein", "Engineering"),
            ("Farrah Finn", "Fine Arts")]
     
def add_new_student(students, name, major):
    students.append((name, major))

def update_student(students, index, name, major):
    students[index] = (name, major)

def find_students_by_name(students, name):
    return [student for student in students if name in student[0]]

def get_all_majors(students):
    return [student[1] for student in students]

What can be concluded from the code snippet above?