二叉树中序遍历 (C语言实现)

     在计算机科学中，树是一种重要的非线性数据结构，直观地看，它是数据元素（在树中称为结点）按分支关系组织起来的结构。二叉树是每个节点最多有两个子树的有序树。通常子树被称作“左子树”（left subtree）和“右子树”（right subtree）。二叉树常被用于实现二叉查找树和二叉堆。

如下是实现创建二叉树和二叉树中序遍历的代码：

 1 #include <stdio.h>

 2 #include <stdlib.h>

 3 #include <memory.h>

 4 

 5 typedef struct _tree_node{

 6     char data;

 7     struct _tree_node * left;

 8     struct _tree_node * right;

 9     struct _tree_node * father;

10 }tree_node;

11 

12 void createTree(tree_node * root);

13 void inorderTraverseTree(tree_node * pRoot);

14 

15 int main()

16 {

17     tree_node root;

18     memset(&root, 0 , sizeof(tree_node));

19     printf("Please create the tree: \n");

20     createTree(&root);

21     printf("The inorder traverse result is: \n");

22     inorderTraverseTree(&root);

23     return 0;

24 }

25 

26 //inorder traversal

27 void inorderTraverseTree(tree_node * pRoot)

28 {

29     tree_node * pCur = pRoot;

30     if(pCur != NULL)

31     {

32         if(pCur->left != NULL)

33         {

34             inorderTraverseTree(pCur->left);

35         }

36         else

37         {

38             printf("%c ", pCur->data);

39             return;

40         }

41         printf("%c ", pCur->data);

42 

43         if(pCur->right != NULL)

44         {

45             inorderTraverseTree(pCur->right);

46         }

47     }

48 }

49 

50 //Create the binary tree

51 void createTree(tree_node * pRoot)

52 {

53     char ch = 0;

54     tree_node * pCur = pRoot;

55     while((ch = getchar())!= 'e')

56     {

57         //printf("%c" , ch);

58         tree_node * pNewNode = (tree_node *)malloc(sizeof(tree_node));

59         pNewNode->left = NULL;

60         pNewNode->right = NULL;

61         pNewNode->father = NULL;

62         if(ch == 'L')

63         {

64             //printf("Input L\n");

65             pNewNode->data = getchar();

66             pNewNode->father = pCur;

67             pCur->left = pNewNode;

68             pCur = pNewNode;

69         }

70         else if(ch == 'R')

71         {

72             //printf("Input R\n");

73             pNewNode->data = getchar();

74             pNewNode->father = pCur;

75             pCur->right = pNewNode;

76             pCur = pNewNode;

77         }

78         else if(ch == 'B')

79         {

80             //printf("Input B\n");

81             free(pNewNode);

82             if(pCur->father != NULL)

83                 pCur = pCur->father;

84             else

85                 printf("It's the top\n");

86         }

87     }

88 }

 

构造这样一颗二叉树：

程序运行结果为：