Data structures and algorithms (6) Binary tree traversal

First, we look at the characteristics of the pre-order, the middle order, and the sequential traversal:
Pre-order Traversal:
1. Access the root node
2. Pre-sequence traversal Zuozi
3. Pre-sequence traversal right subtree
Middle Sequence Traversal:
1. Middle Sequence Traversal Zuozi
2. Access the root node
3. The middle sequence traverses the right sub-tree
Post-post traversal:
1. Post-Zuozi traversal
2. Post-the-loop traversal of right sub-tree
3. Access the root node

First, known pre-order, middle sequence traversal

Pre-sequence traversal: Gdafemhz

Middle Sequence Traversal: ADEFGHMZ

Algorithm Flow:

1 Determine the root, determine the left subtree, and determine the right subtree.

2 recursion in record.

3 recursively in the right subtree.

4 Prints the current root.

The order of sequential traversal is: AEFDHZMG

Programming Implementation:

#include <iostream>#include<fstream>#include<string>struct treenode{struct TreeNode*Left ; struct TreeNode*Right ; CharElem;};voidBinarytreefromorderings (Char* Inorder,Char* Preorder,intlength) {  if(length = = 0)    {      //cout<< "Invalid length";      return; } TreeNode* node =NewTreeNode;//noice that [new] should is written out.Node->elem = *preorder; intRootindex = 0;  for(; rootindex < length; rootindex++)    {      if(Inorder[rootindex] = = *preorder) Break; }  // LeftBinarytreefromorderings (inorder, preorder +1, Rootindex); // RightBinarytreefromorderings (inorder + rootindex + 1, preorder + rootindex + 1, Length-(Rootindex + 1)); cout<<node->elem<<Endl; return;}intMainintargcChar*argv[]) {printf ("Hello world!\n"); Char* pr= "Gdafemhz"; Char* in= "ADEFGHMZ"; Binarytreefromorderings (in, PR,8); printf ("\ n"); return0;}

Second, the known order, the middle sequence traversal, to seek the pre-sequence traversal

Middle Sequence Traversal: ADEFGHMZ

Post-post traversal: AEFDHZMG

Algorithm Flow:

1 Determine the root, determine the left subtree, and determine the right subtree.

2 recursion in record.

3 recursively in the right subtree.

4 Prints the current root.

So, the pre-sequence traversal: Gdafemhz

Programming Implementation:

#include <iostream>#include<fstream>#include<string>struct treenode{struct TreeNode*Left ; struct TreeNode*Right ; CharElem;}; TreeNode* Binarytreefromorderings (Char* Inorder,Char* Aftorder,intlength) {    if(length = = 0)    {        returnNULL; } TreeNode* node =NewTreeNode;//noice that [new] should is written out.Node->elem = * (aftorder+length-1); Std::cout<<node->elem<<Std::endl; intRootindex = 0;  for(; rootindex < length; rootindex++)//a variation of the loop    {        if(Inorder[rootindex] = = * (aftorder+length-1))             Break; } node->left =binarytreefromorderings (inorder, Aftorder, Rootindex); Node->right = binarytreefromorderings (inorder + rootindex + 1, Aftorder + rootindex, Length-(Rootindex + 1)); returnnode;}intMainintargcChar**argv) {    Char* af= "AEFDHZMG"; Char* in= "ADEFGHMZ"; Binarytreefromorderings (In, AF,8); printf ("\ n"); return0;}

Data structures and algorithms (6) Binary tree traversal