Standard 1

Line totals

lines is a list of (item, quantity, price) tuples. Write line_totals(lines) that returns a list of the total for each line.

line_totals([("bread", 3, 25), ("milk", 2, 2.5)])  ->  [75, 5.0]

def line_totals(lines):
    ...

Items over a price

prices maps item names to prices. Write over(prices, limit) that returns the names of items priced strictly above limit, in alphabetical order.

over({"apple": 40, "milk": 2.5, "bread": 25}, 20)  ->  ["apple", "bread"]

def over(prices, limit):
    ...

Initials

Write initials(name) that returns the first letter of each word, in capitals, joined together. The name has at least one word.

initials("ada lovelace")      ->  "AL"
initials("grace brewster hopper")  ->  "GBH"

def initials(name):
    ...

Longest word

sentence has at least one word, separated by spaces. Write longest_word(sentence) that returns its longest word. On a tie, return the first.

longest_word("fresh sourdough bread")  ->  "sourdough"

def longest_word(sentence):
    ...

Stock after sales

stock maps items to quantities and sales is a list of item names, one per item sold. Write after_sales(stock, sales) that reduces each sold item's quantity by one, changing stock itself, and returns it. Every sold item is in stock.

after_sales({"apple": 3, "bread": 2}, ["apple", "bread", "apple"])  ->  {"apple": 1, "bread": 1}

def after_sales(stock, sales):
    ...

Unique, in order

Write unique(items) that returns a new list with duplicates removed, keeping the first occurrence of each item and the original order.

unique(["apple", "bread", "apple", "milk", "bread"])  ->  ["apple", "bread", "milk"]

def unique(items):
    ...

Palindrome, ignoring case and spaces

Write is_palindrome(text) that returns True if the text reads the same backwards, ignoring capital letters and spaces.

is_palindrome("Was it a cat I saw")  ->  True
is_palindrome("bread")               ->  False

def is_palindrome(text):
    ...

Serve some customers

arrivals is a list of names in arrival order. Write remaining(arrivals, n) that serves the first n customers from a deque and returns a list of who is still waiting. If n is more than the number of customers, nobody is left. Leave arrivals itself unchanged.

remaining(["Ada", "Grace", "Linus"], 2)  ->  ["Linus"]
remaining(["Ada"], 5)                    ->  []

from collections import deque

def remaining(arrivals, n):
    ...

Letter counts

Write letter_counts(text) that returns a dictionary mapping each character in text to how many times it appears, ignoring spaces.

letter_counts("a bad cab")  ->  {"a": 3, "b": 2, "d": 1, "c": 1}

def letter_counts(text):
    ...

Capitalise each word

Write title_case(text) that capitalises the first letter of every word and lowercases the rest. Words are separated by single spaces.

title_case("fresh SOURDOUGH bread")  ->  "Fresh Sourdough Bread"

def title_case(text):
    ...

Next: Standard 2.