Microsoft Data Science Internship Code Challenges & Tips

1. Write a function that takes a list of integers and returns the two numbers that add up to a specified target. If no such numbers exist, return an empty list.

2. Implement a function that calculates the median of a list of numbers. The function should handle both even and odd lengths of the list.

3. Given a string, write a function that finds the first non-repeating character in it. If all characters are repeating, return None.

4. Write a function to sort a list of dictionaries based on a specific key in descending order.

5. Implement a function that checks if a given binary tree is a valid binary search tree (BST).

6. Given a list of integers, write a function that returns the length of the longest consecutive sequence of integers.

7. Write a function that finds the Kth largest element in an unsorted array of integers.

8. Implement a function to perform k-means clustering on a given 2D dataset represented as a list of tuples.

9. Write a function to implement a simple linear regression model from scratch using gradient descent.

10. Given a dataset containing features and a target variable, write a function that splits the data into training and testing sets with a specified ratio.