随机二叉树中的插入函数 [英] Insertion function in a random binary tree

问题描述

我在C ++中的此二叉树中的插入函数遇到问题.节点已正确插入，直到需要再次在右侧或左侧添加一个节点为止.该功能认为在我已经在那些位置插入节点的情况下，我的左侧或右侧没有任何节点.

I'm having a problem with my insertion function in this binary tree in C++. The nodes are correctly inserted until I need to add again a node to the right or to the left. The function thinks I don't have any nodes to either the left or the right in the case being that I already inserted nodes in those places.

这是我的代码:

void insert(string data)
{    
    srand(time(NULL));
    int r;
    node *aux=head;
    node *n=new node(data);
    if (head==NULL)
    {
        head =n;
        return;
    }

    while (aux!=NULL)
    { 
        r=rand()%100;
        if (r>50)
        {
            cout<<"\nRandom is "<<r<<", Therefore we have to go to the right."<<endl;
            aux=aux->right;  
        }
        else
        {   
            cout<<"\nRandom is "<<r<<", Therefore we have to go to the left."<<endl;
            aux=aux->left;
            if (aux!=NULL)
            {
                cout<<aux->getdata()<<endl;
            }
        }
    }

    aux=n;
    cout<<"\nWe insert "<<aux->getdata()<<endl;
}

推荐答案

以下是您的代码的略微修改:

Here's a slight modification of your code:

void insert(string data)
      {    srand(time(NULL));
           int r;
           node *aux=head;
           node *n=new node(data);
           if(head==NULL){
                          head =n;
                          return;
                          }

       while(aux!=NULL) // We could put while(true) here.
       { 
                       r=rand(); // Modulo is a somehow slow operation
                       if((r  & 1 )== 0) // This is much faster. It checks if r is even
                       {  cout<<"\nRandom is "<<r<<", which is even therefore we have to go to the right."<<endl;
                          if ( aux->right == NULL) // We found an empty spot, use it and break
                          {
                              aux->right = n; break;
                          }
                          else // else move to the right child and continue
                          {
                              aux=aux->right;  
                              cout<<aux->getdata()<<endl;
                          }
                       }
                       else
                       {   
                           cout<<"\nRandom is "<<r<<", which is odd Therefore we have to go to the left."<<endl;
                          if ( aux->left == NULL) // We found an empty spot, use it and break
                          {
                              aux->left = n; break;
                          }
                          else // else move to the left child and continue
                          {
                              aux=aux->left;  
                              cout<<aux->getdata()<<endl;
                          }

                       }
       }
       cout<<"\nWe insert "<<n->getdata()<<endl;

  }

主要原因是您滥用辅助功能.这是一个示例，希望对您有所帮助:

THe main reason is that you are misusing aux. Here's an example which I hope will help you identify your mistake:

node * aux = head; // suppose head doesn't have any child node
node * n = new node(data);

aux = aux->left; // Set aux to point on the left child of head
aux = n; // Set aux to point on n

cout << aux == NULL?"Aux is null":"Aux is not null" << endl;
cout << head->left == NULL?"Left is null":"Left is not null" << endl;

此代码应返回:

Aux is not null
Left is null

原因是，当我们将 n 分配给 aux 时，我们只是告诉 aux 指向 n 而不是指向左侧节点.我们没有将 n 分配为head的左侧孩子.

The reason is that when we assigned n to aux, we simply told aux to point on n instead of pointing on the left node. We didn't assign n to be the left child of head.

您也可以通过将aux声明为node的指针来解决此问题.

You could also solve this issue by declaring aux to be a pointer of a pointer of node.

node * * aux = &head;

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