二叉树有序遍历显示错误

Question

The display for my binary tree in-order traversal is wrong. I cant figure out what I'm doing wrong. The output is showing up at 1-15 when the height is 4 (including level 0 as 1) instead of showing up as : 8 4 9 2 10 5 11 1 12 6 13 3 14 7 15.

main:

#include <iostream>
#include "math.h"
#include "bintree.h"
using namespace std;

int main()
{
    binary_tree bin;
    int tmp, num, height;

        cout << "Please enter a height that you wish to see: " ;
        cin >> height;
        cout << endl << endl;

        bin.insert(num, height);

        cout << "The In-Order Traversal is: " ;
        bin.displayinorder();
        cout << endl << endl;



    system("Pause");
    return 0;
}

void binary_tree::insert(int num, int height)
{
  num = pow(2, height);

  for(int i = 1; i < num; i++)
  {
     node* t = new node;
     node* parent;
     t-> data = i;
     t-> left = NULL;
     t-> right = NULL;
     parent = NULL;

     if(isEmpty()) root = t;
     else
     {
         node* curr;
         curr = root;

         while(curr)
         {
             parent = curr;
             if(t->data > curr->data) curr = curr->right;
             else curr = curr->left;
         }

         if(t->data < parent->data)
            parent->left = t;
         else
            parent->right = t;
      }
   }
}


void binary_tree::displayinorder()
{
  inorder(root);
}

void binary_tree::inorder(node* p)
{
    if(p)
    {
        inorder(p -> left);
        cout<< " " << p->data <<" ";
        inorder(p -> right);
    }
}

void binary_tree::displaypreorder()
{
    preorder(root);
}

void binary_tree::preorder(node* p)
{
    if(p != NULL)
    {
        cout<<" "<< p -> data <<" ";
        preorder(p -> left);
        preorder(p -> right);
    }
    else return;
}

header:

#ifndef BINTREE_H
#define BINTREE_H
#include <cstdlib>  // Provides NULL and size_t

   class binary_tree
   {
      private:
       struct node
       {
          node* left;
           node* right;
           int data;
       };
      node* root;

    public:
        binary_tree()
        {
           root = NULL;
        }

        bool isEmpty() const 
        { 
             return root==NULL; 
        }

        void displayinorder();
        void inorder(node*);

        void displaypreorder();
        void preorder(node*);

        void insert(int, int);
};

#endif

Answer 1

I think you are unclear what in-order means. 1 .. 15 is the expected output for in-order traversal of a binary search tree containing the values 1 .. 15. The sequence you gave sounds like pre-order on a balanced binary search tree.

In other words, your traversal code is correct for in-order traversal.

That said, your tree generation code does not produce a balanced tree. An in-order traversal won't expose that, but a pre-order or post-order traversal will. Because you insert all of the values in increasing sequential order, you will get a tree made entirely of right children. Add some cout statements to your traversal to see what I mean.