Python Code Challenges & Tips

1. Write a Python function that takes a string and returns the string in camel case format.

2. Implement a function that takes a list of integers and returns the maximum product of any two distinct numbers from the list.

3. Given a list of integers, write a function that returns a list with all unique elements that occur more than once.

4. Write a function to check if a given string is a valid palindrome, considering only alphanumeric characters and ignoring cases.

5. Implement a function that takes a binary tree and returns its maximum depth.

6. Write a Python function that counts the number of occurrences of each character in a given string and returns the result as a dictionary.

7. Given a list of integers, write a function that returns a new list containing only the elements that are greater than the average of the original list.

8. Implement a function that finds the longest substring without repeating characters in a given string.

9. Write a function that takes a list of words and returns the longest word that can be formed by concatenating two or more words from the same list.

10. Given a string of parentheses, write a function to determine if the string is valid (i.e., every opening bracket has a corresponding closing bracket).