Classify Tree Traversal Algorithms. Provide some visual explanation.

Tree traversal algorithms are methods used to visit all the nodes in a tree data structure systematically. These algorithms can be broadly classified into two main categories: Depth-First Search (DFS) and Breadth-First Search (BFS). Each category has its own set of traversal techniques.

Depth-First Search (DFS) Traversals

DFS traversals explore as far down a branch as possible before backtracking. There are three primary types of DFS traversals:

1. Inorder Traversal (Left, Root, Right)

In an inorder traversal, the nodes are visited in the following order:

1. Visit the left subtree.
2. Visit the root node.
3. Visit the right subtree.

Visual Explanation:
Consider the following binary tree:

      A
     / \
    B   C
   / \   \
  D   E   F

Inorder traversal of this tree would visit the nodes in the order: D, B, E, A, C, F.

2. Preorder Traversal (Root, Left, Right)

In a preorder traversal, the nodes are visited in the following order:

1. Visit the root node.
2. Visit the left subtree.
3. Visit the right subtree.

Visual Explanation:
Using the same tree:

      A
     / \
    B   C
   / \   \
  D   E   F

Preorder traversal of this tree would visit the nodes in the order: A, B, D, E, C, F.

3. Postorder Traversal (Left, Right, Root)

In a postorder traversal, the nodes are visited in the following order:

1. Visit the left subtree.
2. Visit the right subtree.
3. Visit the root node.

Visual Explanation:
Using the same tree:

      A
     / \
    B   C
   / \   \
  D   E   F

Postorder traversal of this tree would visit the nodes in the order: D, E, B, F, C, A.

Breadth-First Search (BFS) Traversal

BFS traversal explores all nodes at the present depth level before moving on to nodes at the next depth level. The primary type of BFS traversal is:

Level Order Traversal

In level order traversal, the nodes are visited level by level from left to right.

Visual Explanation:
Using the same tree:

      A
     / \
    B   C
   / \   \
  D   E   F

Level order traver...