Deduplicate, keep order
Remove repeats while keeping each value's first occurrence. Target O(n) average time.
What you’ll practice
This Level 1 exercise focuses on lists + sets in the Core Python curriculum. Solve the challenge prompt above using clear, idiomatic Python and the relevant language or standard-library tools.
Relevant Python reference: Lists, Set Types — set, frozenset.
Sample Test Cases
dedupe([4, 2, 4, 1, 2, 3])[4,2,1,3]Further Reading
Reference Solution
Reveal Reference Solution
def dedupe(values: list[int]) -> list[int]: seen, result = set(), [] for value in values: if value not in seen: seen.add(value) result.append(value) return resultPro Tips & Keyboard Shortcuts
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