Challenges to do

[vincepmartin]

• [x] https://leetcode.com/problems/balanced-binary-tree/description/ (come back to this!)
• [x] https://leetcode.com/problems/merge-two-binary-trees/description/
• [ ] https://leetcode.com/problems/intersection-of-two-linked-lists/description/
• [x] https://leetcode.com/problems/single-number/description/
• [x] https://leetcode.com/problems/invert-binary-tree/description/
• [ ] https://leetcode.com/problems/reverse-linked-list/description/

[vincepmartin]

• [ ] https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/description/