Coding Challenges

Write a function that takes a non-negative integer and returns the sum of its digits.

Build a full-featured to-do list app using JavaScript and local storage.

Create a function to check if a number is prime. Push your limits with large inputs.

Write a function that reverses a string and handles edge cases gracefully.

Solve the Fibonacci sequence using dynamic programming. Optimize both time and space complexity.

Find the missing number in an array of 0 to n values.

Check if a string is a valid palindrome (ignore non-alphanumeric).

Check if a number is a power of two.

Return all possible permutations of a list of numbers.