Challenge — Code Wars · Speed Round

By the end of this lesson you can:

• Translate a short English brief into a working Python function in under five minutes.
• Recognise which Level 1 tool fits each problem (string method, list method, loop, condition, function).
• Decide when to stop polishing and move on — "works and tested" is the bar, not "perfect".

Open speed_round.py. Set a timer for 40 minutes (4 minutes per problem). Three rules:

1. Don't plan. Read the brief, type something straight away, fix as you go. Planning is a luxury for slower problems.
2. Use the test at the bottom. Each problem comes with one assertion you can paste in. If it passes silently, you're done. If it raises AssertionError, fix and retry.
3. If stuck for more than 4 minutes, skip. Mark with TODO and move on. Come back at the end.

Aim for 7/10 by the timer. 9/10 is excellent. 10/10 means you're ready for the capstone.

Problem 1 · add(a, b)

Return the sum of two numbers.

# Test
assert add(2, 3) == 5
assert add(-1, 1) == 0

Problem 2 · last_letter(word)

Return the last letter of word. Use a slice or negative index.

# Test
assert last_letter("python") == "n"
assert last_letter("a") == "a"

Problem 3 · is_even(n)

Return True if n is even, else False.

# Test
assert is_even(0) == True
assert is_even(7) == False
assert is_even(-4) == True

Problem 4 · count_vowels(text)

Return how many vowels (a, e, i, o, u — any case) are in text.

# Test
assert count_vowels("hello") == 2
assert count_vowels("PYTHON") == 1
assert count_vowels("xyz") == 0

Problem 5 · shout(text)

Return text uppercase with three exclamation marks at the end.

# Test
assert shout("hi") == "HI!!!"
assert shout("nasi lemak") == "NASI LEMAK!!!"

Problem 6 · biggest(nums)

Return the largest item in a non-empty list. Don't use the built-in max.

# Test
assert biggest([3, 1, 4, 1, 5, 9, 2, 6]) == 9
assert biggest([-7, -3, -10]) == -3
assert biggest([42]) == 42

Problem 7 · reverse(text)

Return text spelled backwards. One-line slice from PY-L1-24.

# Test
assert reverse("malam") == "malam"
assert reverse("hello") == "olleh"
assert reverse("") == ""

Problem 8 · average(nums)

Return the average of a list of numbers. Return 0 for an empty list.

# Test
assert average([10, 20, 30]) == 20
assert average([1, 2, 3, 4]) == 2.5
assert average([]) == 0

Problem 9 · count_word(text, word)

Return how many times word appears in text. Case-insensitive. Use the string method .count() after lower-casing both sides.

# Test
assert count_word("Selamat datang ke Selamat Hub", "selamat") == 2
assert count_word("hello world", "x") == 0
assert count_word("AaAaA", "a") == 5

Problem 10 · fizz_buzz_list(n)

Return a list of strings — for each i from 1 to n inclusive, the FizzBuzz value (as in PY-L1-34 event 10).

# Test
assert fizz_buzz_list(5) == ["1", "2", "Fizz", "4", "Buzz"]
assert fizz_buzz_list(15)[-1] == "FizzBuzz"
assert fizz_buzz_list(0) == []

Try them yourself first. Only open this section after you've attempted all ten (or run out of time). The point is not to copy — it's to compare your approach to a fast one.

def add(a, b):
    return a + b

def last_letter(word):
    return word[-1]

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

def count_vowels(text):
    n = 0
    for ch in text.lower():
        if ch in "aeiou":
            n = n + 1
    return n

def shout(text):
    return text.upper() + "!!!"

def biggest(nums):
    answer = nums[0]
    for x in nums:
        if x > answer:
            answer = x
    return answer

def reverse(text):
    return text[::-1]

def average(nums):
    if len(nums) == 0:
        return 0
    return sum(nums) / len(nums)

def count_word(text, word):
    return text.lower().count(word.lower())

def fizz_buzz_list(n):
    result = []
    for i in range(1, n + 1):
        if i % 15 == 0:
            result.append("FizzBuzz")
        elif i % 3 == 0:
            result.append("Fizz")
        elif i % 5 == 0:
            result.append("Buzz")
        else:
            result.append(str(i))
    return result

Most of these are 1-4 lines. The longest is fizz_buzz_list at 11 lines, and even that's mostly the four branches of the FizzBuzz if. The skill being trained today is not cleverness — it's economy of motion. Pick the right tool, type it, test it, move on.

Open your timer's log if it had one, otherwise estimate. Answer in your head:

• How many did you finish before the timer? Score: __ / 10
• How many were "working but ugly" — would you rewrite if you had time? That's actually a healthy sign.
• Which one took you the longest? Why — was it new vocabulary, or did you take the long path?

If you scored under 5/10: re-read PY-L1-31 (list helpers) and PY-L1-23 (string methods) before the capstone — most of today's problems are direct calls to those.

Code Wars is over. Three rounds, three angles on the same skill — read code (bug hunt), trace code (predict the output), write code (speed round). The common thread is calmness: most Level 1 problems are 1-5 lines of body, and over-thinking is the biggest blocker. Each of today's ten problems was a direct call to a tool you've had for weeks — slicing, %, the in operator, .count(), .upper(), a for-loop with an accumulator. Tomorrow we start the three-part Number Guesser, which is the warm-up for the Level 1 capstone.