c++实现二叉搜索树

自己实现了一下二叉搜索树的数据结构，记录一下：

#include <iostream>

using namespace std;

struct TreeNode{
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int value) { val=value; left=NULL; right=NULL; }
};

class SearchTree{

public:
SearchTree();
~SearchTree();
void Destory(TreeNode *);
void Insertnode(int);
void Preorder(TreeNode *);
void Inorder(TreeNode *);
void Postorder(TreeNode *);
void Predisplay();
void Indisplay();
void Postdisplay();
private:
TreeNode *root;

};

SearchTree::SearchTree()
{
root=NULL;
}

SearchTree::~SearchTree()
{
cout<<"析构二叉搜索树："<<endl;
Destory(root);
}

void SearchTree::Destory(TreeNode *node)
{
if(node!=NULL)
{
Destory(node->left);
Destory(node->right);
cout<<node->val<<" ";
delete node;
}
}

void SearchTree::Insertnode(int value)
{
if(root==NULL)
root=new TreeNode(value);
else
{
TreeNode *p,*pre;
pre=p=root;
while(p)
{
if(p->val==value)
return;
else if(p->val>value)
{
pre=p;
p=p->left;
}
else
{
pre=p;
p=p->right;
}

}
p=new TreeNode(value);
if(pre->val>value)
pre->left=p;
else
pre->right=p;
}
}

void SearchTree::Predisplay()
{
Preorder(root);
}

void SearchTree::Preorder(TreeNode *root)
{
if(root)
{
cout<<root->val<<" ";
Preorder(root->left);
Preorder(root->right);
}
}

void SearchTree::Indisplay()
{
Inorder(root);
}

void SearchTree::Inorder(TreeNode *root)
{
if(root)
{
Inorder(root->left);
cout<<root->val<<" ";
Inorder(root->right);
}
}

void SearchTree::Postdisplay()
{
Postorder(root);
}

void SearchTree::Postorder(TreeNode *root)
{
if(root)
{
Postorder(root->left);
Postorder(root->right);
cout<<root->val<<" ";
}
}

int main()
{
SearchTree t;
int a[]={7,4,2,3,15,35,6,45,55,20,1,14};
int n=sizeof(a)/sizeof(a[0]);
cout<<"构造二叉搜索树："<<endl;
for(int i=0;i<n;++i)
{
cout<<a[i]<<" ";
t.Insertnode(a[i]);
}
cout<<endl<<"先序遍历序列: "<<endl;
t.Predisplay();
cout<<endl<<"中序遍历序列: "<<endl;
t.Indisplay();
cout<<endl<<"后序遍历序列: "<<endl;
t.Postdisplay();
cout<<endl;
return 0;
}