Tree

Tree Problems

Divide & Conquer -> Sub Problems -> Recursive & Iterative

Recursive Approach

1. Find out the best base case
2. Deal with the result (return) of sub-problems
3. Solve sub-problems, finally

• Invert Binary Tree

• Flatten Binary Tree to Linked List

• Maximum & Minimum Depth of Binary Tree

Iterative Approach

1. What previous value (state) to store
2. When to use the stored value
3. When to update the stored value

• Binary Tree Inorder Traversal

Traverse

• Pre-order
• In-order

  https://leetcode.com/problems/binary-tree-inorder-traversal

• Post-order

  https://leetcode.com/problems/binary-tree-postorder-traversal

• Level-order

  https://leetcode.com/problems/binary-tree-level-order-traversal