Practice
Your code is run against real test cases and marked the moment you submit. Start with the easy ones — they are genuinely easy, not “easy for somebody who already knows”.
You can solve anything here without an account. Signing up is what remembers which ones you have finished, keeps your streak and pays the coins.
1
Hard
Remove Duplicates
1 solved
Solve
2
Hard
Anagram Check
1 solved
Solve
3
Hard
Binary Search
2 solved
Solve
New to this?
Every problem gives you starter code in five languages, shows a worked example, and tells you exactly which test your program failed on — not just that it failed.
If a problem looks unfamiliar, read the tutorial on that topic first. They are meant to be used together: read, then solve, then read the next one.