About this challenge
Remove Duplicate Characters is a easy string manipulation coding challenge. It tests string-manipulation techniques: parsing, transforming, and searching text efficiently. Write your solution in the editor above, run it against the test cases, and get instant feedback — free, in your browser, no sign-up.
Show a hint & approach (spoiler)
Hint: Walk the string, collect characters into a Set and an output array; only append when the Set did not already contain the char.
Keep practicing
Browse all coding challenges, or build intuition for the underlying concepts with the algorithm visualizers and the developer cheatsheets.