Data structure-traversal of a two-tree (c-language descriptive narrative)

Traversal concepts

The so-called traversal (traversal) refers to a search route along a path. Make one visit to each node in the tree in turn. The operation of the Access node relies on a detailed application issue.

Traversal is one of the most important operations on a two-fork tree, and is the basis for other operations on a two-fork tree.

Traversal scenarios

1. Traversal scenarios
From the recursive definition of the two-fork tree, a non-empty two-fork tree consists of three basic parts, the root node and the left and right subtree. So. At any given node, you can run three operations in some order:
(1) The interview node itself (N),
(2) Zuozi (L) traversing the node,
(3) The right sub-tree (R) of the node is traversed.
There are six operating sequences for the above three operations:
NLR, LNR, LRN, NRL, RNL, RLN.

Attention:
The first three sequences are symmetrical with the latter three. So we only discuss the first three order of left and right.

2. Three types of traversal naming
Based on the location of the Access node operation name:
① NLR: Pre-order traversal (Preordertraversal also called (sequential traversal))
--The operation of the access node occurs before traversing its left and right subtrees.
② LNR: Middle sequence Traversal (inordertraversal)
--The operation of the access node occurs in the traversal of its left and right subtree (between).

③ LRN: Post-post traversal (postordertraversal)
--access node operations occur after traversing their left and right subtrees.
Attention:
Because the node being interviewed must be the root of a subtree. So N (Node), L (left Subtlee), and R (right subtree) can be interpreted as the root, the Zoki of the root.

The

NLR, LNR, and LRN are also known as first-root traversal, middle-root traversal, and post-root traversal, respectively.


Traversal algorithm

1. Recursive algorithm definition for middle order traversal:
    If the binary tree is not empty. Run the following actions, for example:
          (1) to traverse the left subtree.
          (2) Visit the root node;
          (3) traverse the right subtree.

2. Recursive algorithm definition of the first order traversal:
    If the binary tree is not empty, then run the following actions, for example:
          (1) To access the root node;
          (2) Traverse left subtree,
          (3) Traverse right subtree.

3. The recursive algorithm for post-routing traversal is defined:
If the binary tree is not empty. Then run the following operations, for example:
(1) traverse the left subtree.
(2) Traverse right subtree.
(3) Visit the root node.

4. Algorithm implementation of Middle sequence traversal
Using binary linked list as storage structure, the middle sequence traversal algorithm can be described as:
void Inorder (Bintree T)
{///algorithm ①~⑥ is to illustrate the increase in the operation of the label
①if (T) {//Assuming that the binary tree is not empty
②inorder (T->lchild);
③printf ("%c", T->data). Interview node
④inorder (T->rchild);
⑤}
⑥}//Inorder

Data structure-traversal of a two-tree (c-language descriptive narrative)