二叉树的遍历

二叉树的遍历

   
     

    
      
    
      #include
    
      "
    
      iostream
    
      "
    
      
#include
    
      "
    
      stdlib.h
    
      "
    
      

    
      using
    
       
    
      namespace
    
       std;


    
      struct
    
       tree
{
 
    
      int
    
       data;
 
    
      struct
    
       tree 
    
      *
    
      left;
 
    
      struct
    
       tree 
    
      *
    
      right;
};

typedef 
    
      struct
    
       tree treenode;
typedef treenode 
    
      *
    
      btree;



    
      /*
    
      ------插入二叉树的结点-------
    
      */
    
      
btree insertnode(btree root,
    
      int
    
       value)
{
 btree newnode;
 btree current;
 btree back;


 
    
      /*
    
      ---创建新结点内存---
    
      */
    
      

 newnode
    
      =
    
      (btree)malloc(
    
      sizeof
    
      (treenode));
 newnode
    
      ->
    
      data
    
      =
    
      value;
 newnode
    
      ->
    
      right
    
      =
    
      NULL;
 newnode
    
      ->
    
      left
    
      =
    
      NULL;

 
    
      if
    
      (root
    
      ==
    
      NULL)
 {
 
    
      return
    
       newnode;
 }
 
    
      else
    
       
 {
 current
    
      =
    
      root;
 
    
      while
    
      (current
    
      !=
    
      NULL)
 {
 back
    
      =
    
      current;
 
    
      if
    
      (current
    
      ->
    
      data
    
      >
    
      value)
 current
    
      =
    
      current
    
      ->
    
      left;
 
    
      else
    
       
 current
    
      =
    
      current
    
      ->
    
      right;
 }
 
    
      if
    
      (back
    
      ->
    
      data
    
      >
    
      value)
 back
    
      ->
    
      left
    
      =
    
      newnode;
 
    
      else
    
      
 back
    
      ->
    
      right
    
      =
    
      newnode;
 }
 
    
      return
    
       root;
}


    
      /*
    
      ------创建二叉树--------
    
      */
    
      

btree createbtree(
    
      int
    
       
    
      *
    
      data, 
    
      int
    
       len)
{
 btree root 
    
      =
    
      NULL;
 
    
      int
    
       i;
 
    
      for
    
      (i
    
      =
    
      0
    
      ;i
    
      <
    
      len;i
    
      ++
    
      )
 root
    
      =
    
      insertnode(root,data[i]);
 
    
      return
    
       root;
}

    
      /*
    
      -----中序遍历------
    
      */
    
      

    
      void
    
       inorder( btree ptr)
{
 
    
      if
    
      (ptr
    
      !=
    
      NULL)
 {
 inorder(ptr
    
      ->
    
      left);
 printf(
    
      "
    
      [%2d]\n
    
      "
    
      ,ptr
    
      ->
    
      data);
 inorder(ptr
    
      ->
    
      right);
 }
}

    
      /*
    
      -----------------------
    
      */
    
      


    
      /*
    
      --------前序遍历-------
    
      */
    
      


    
      void
    
       preorder(btree ptr)
{
 
    
      if
    
      (ptr
    
      !=
    
      NULL)
 {
 
 printf(
    
      "
    
      [%2d]\n
    
      "
    
      ,ptr
    
      ->
    
      data);
 inorder(ptr
    
      ->
    
      left);
 inorder(ptr
    
      ->
    
      right);
 }
}

    
      /*
    
      -----------------------------
    
      */
    
      


    
      /*
    
      ------后序遍历--------
    
      */
    
      


    
      void
    
       postorder(btree ptr)
{
 
    
      if
    
      (ptr
    
      !=
    
      NULL)
 {
 
 inorder(ptr
    
      ->
    
      left);
 inorder(ptr
    
      ->
    
      right);
 printf(
    
      "
    
      [%2d]\n
    
      "
    
      ,ptr
    
      ->
    
      data);
 
 }
}

    
      /*
    
      ---------------------------
    
      */
    
      


    
      /*
    
      ---------主程序-----
    
      */
    
      


    
      int
    
       main()
{
 btree root
    
      =
    
      NULL;

 
    
      int
    
       data[
    
      9
    
      ]
    
      =
    
      {
    
      5
    
      ,
    
      6
    
      ,
    
      4
    
      ,
    
      8
    
      ,
    
      2
    
      ,
    
      3
    
      ,
    
      7
    
      ,
    
      1
    
      ,
    
      9
    
      };
 root 
    
      =
    
      createbtree(data,
    
      9
    
      );
 printf(
    
      "
    
      树的结点内容：\n
    
      "
    
      );
 inorder(root);
 cout
    
      <<
    
      endl;
 preorder(root);
 cout
    
      <<
    
      endl;
 postorder(root);
 cout
    
      <<
    
      endl;

}