二叉树与二叉排序树的创建

创建二叉树

#include <iostream>
using namespace std;

struct TreeNode
{
    int val;
    TreeNode *left,*right;
};

/*void preOrderTraverse(TreeNode *p)
{
    if(p)
    {
        cout<<p->val<<" ";
        preOrderTraverse(p->left);
        preOrderTraverse(p->right);
    }
}*/

void create(TreeNode *&p)
{
    int k;
    cin>>k;
    if(k!=0)
    {
        p=new TreeNode;
        p->val=k;
        create(p->left);
        create(p->right);
    }
    else
        p=NULL;
}

int main()
{
    TreeNode *root=NULL;
    create(root);

    //preOrderTraverse(root);
}

创建二叉排序树

#include <iostream>
using namespace std;

struct TreeNode
{
    int val;
    TreeNode *left,*right;
};
void Insertnode(TreeNode *&p,int k)
{
    if(p==NULL)
    {
        p=new TreeNode;
        p->val=k;
        p->left=p->right=NULL;
        return;
    }
    /*if(k==p->val)  BST中不能有相等的值
        return;*/
    if(k<p->val)
        Insertnode(p->left,k);
    else
        Insertnode(p->right,k);
}

/*void CreateTree(TreeNode *root,int a[],int n)
{
    root=NULL;
    int i;
    for(i=0;i<n;i++)
    {
        Insertnode(root,a[i]);
    }
}*/

void preOrderTraverse(TreeNode *p)
{
    if(p)
    {
        cout<<p->val<<" ";
        preOrderTraverse(p->left);
        preOrderTraverse(p->right);
    }
}

int main()
{
    int a[]={5,7,1,3,9,2,0,4,8,6};
    int i,n=10;
    TreeNode *root=NULL;
    for(i=0;i<n;i++)
        Insertnode(root,a[i]);

    preOrderTraverse(root);
    cout<<endl;

    return 0;
}