Question

我正在尝试使用指针在c ++中实现一个简单的二叉树。

我已经成功实现了插入和遍历，但是当我尝试删除节点时遇到了一些问题：

我的主要功能是：

main(){
node* root=createNode(1);
root->left=createNode(2);
root->right=createNode(3);
root->left->left=createNode(4);
root->left->right=createNode(5);
root->right->left=createNode(6);
root->right->right=createNode(7);
inorder(root);
//till here it works fine

delete root->left->left;     //problem starts here
cout<<"\n";
inorder(root);               //exception is thrown here...
return 0;

} `

inorder函数是非常基本的递归函数：

void inorder(node* root){
if(root!=NULL){
    inorder(root->left);
    cout<<root->data<<" ";
    inorder(root->right);
}
}

有人能告诉我删除行有什么问题吗？

Answer 1

在delete之后，尝试访问已删除的指针将导致此问题。您可能想要添加

root->left->left = 0

删除行后。

Answer 2

您必须将root->left->left指针设置为NULL，即它指向什么

在你的代码中

main()
{
   node* root=createNode(1);
   root->left=createNode(2);
   root->right=createNode(3);
   root->left->left=createNode(4);
   root->left->right=createNode(5);
   root->right->left=createNode(6);
   root->right->right=createNode(7);
   inorder(root);
   //Now, Complete program will work

   delete root->left->left =  0;     //problem solved
   cout<<"\n";
   inorder(root);               // Do you still face any problem ?
   return 0;
}

Answer 3

删除节点后，需要将父节点的左指针重置为零。不这样做会导致不可预测的结果，具体取决于内存管理的实现方式。有些系统对引用释放内存的引用有异常

Answer 4

Your trying to delete node which has not null nodes in both right and left side, so you to delete node like this ..

/* deletes a node from the binary search tree */
void delete ( struct btreenode **root, int num )
{
    int found ;
    struct btreenode *parent, *x, *xsucc ;

    /* if tree is empty */
if ( *root == NULL )
    {
        printf ( "\nTree is empty" ) ;
        return ;
    }

    parent = x = NULL ;

    /* call to search function to find the node to be deleted */

    search ( root, num, &parent, &x, &found ) ;

    /* if the node to deleted is not found */
if ( found == FALSE )
    {
        printf ( "\nData to be deleted, not found" ) ;
        return ;
    }

    /* if the node to be deleted has two children */
if ( x -> leftchild != NULL && x -> rightchild != NULL )
    {
        parent = x ;
        xsucc = x -> rightchild ;

        while ( xsucc -> leftchild != NULL )
        {
            parent = xsucc ;
            xsucc = xsucc -> leftchild ;
        }

        x -> data = xsucc -> data ;
        x = xsucc ;
    }

    /* if the node to be deleted has no child */
if ( x -> leftchild == NULL && x -> rightchild == NULL )
    {
        if ( parent -> rightchild == x )
            parent -> rightchild = NULL ;
        else
            parent -> leftchild = NULL ;

        free ( x ) ;
        return ;
    }

    /* if the node to be deleted has only rightchild */
if ( x -> leftchild == NULL && x -> rightchild != NULL )
    {
        if ( parent -> leftchild == x )
            parent -> leftchild = x -> rightchild ;
        else
            parent -> rightchild = x -> rightchild ;

        free ( x ) ;
        return ;
    }

    /* if the node to be deleted has only left child */
if ( x -> leftchild != NULL && x -> rightchild == NULL )
    {
        if ( parent -> leftchild == x )
            parent -> leftchild = x -> leftchild ;
        else
            parent -> rightchild = x -> leftchild ;

        free ( x ) ;
        return ;
    }
}

如何删除树中的节点？

4 个答案: