pythonLogic errorEasy

Removing duplicate items with set scrambles original order

Time: 0:00

BugFind the bug and fix the code

What it should do

deduplicate_preserve_order(items) removes duplicates while preserving the original appearance order. Example: deduplicate_preserve_order(["b", "a", "c", "a"]) → ["b", "a", "c"].

What happens instead

deduplicate_preserve_order(["b", "a", "c", "a"]) returns ["a", "c", "b"] with scrambled element order.

def deduplicate_preserve_order(items):
    return list(set(items))

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

⏱️0:00

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Hint 3

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This bug belongs to the logic errors pattern

The wrong operator, an inverted condition, a formula the right way round but backwards.

Learn the logic errors pattern Step through your own code

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pythonLogic errorEasy

Removing duplicate items with set scrambles original order

Time: 0:00

BugFind the bug and fix the code

What it should do

deduplicate_preserve_order(items) removes duplicates while preserving the original appearance order. Example: deduplicate_preserve_order(["b", "a", "c", "a"]) → ["b", "a", "c"].

What happens instead

deduplicate_preserve_order(["b", "a", "c", "a"]) returns ["a", "c", "b"] with scrambled element order.

def deduplicate_preserve_order(items):
    return list(set(items))

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

⏱️0:00

Hints

🏆 0 hints = Flawless Solve

Think & Test Cooldown

2:00 remaining

Take a moment to read the bug symptom and trace the code with Run & Check before unlocking Hint 1.

Hint 2

Unlocks after Hint 1

Hint 3

Unlocks after Hint 2

This bug belongs to the logic errors pattern

The wrong operator, an inverted condition, a formula the right way round but backwards.

Learn the logic errors pattern Step through your own code

Removing duplicate items with set scrambles original order

What it should do

What happens instead

More logic errors to practise

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Removing duplicate items with set scrambles original order

What it should do

What happens instead

More logic errors to practise

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