Question

我的删除功能无法正常工作。当它删除节点时，它不会重新平衡整个树。有时它会平衡左子树，但省略整个右子树。代码很长

class AVLTree
{
public:
    void insert(const DataType &item);
    void graph(ostream &out) const;
    void remove(DataType &value);
private:
    class AVLNode
    {
    public:
        DataType data;
        int balanceFactor;
        AVLNode *left;
        AVLNode *right;
        AVLNode():balanceFactor(0),left(NULL),right(NULL){}
        AVLNode(DataType item):balanceFactor(0), data(item),left(NULL), right(NULL){}
    };
    typedef AVLNode* AVLNodePointer;
    AVLNodePointer myRoot;
    int height(AVLTree<DataType>::AVLNodePointer temp);
    int different(AVLTree<DataType>::AVLNodePointer temp);
    AVLNodePointer ll_rotation(AVLTree<DataType>::AVLNodePointer parent);
    AVLNodePointer rr_rotation(AVLTree<DataType>::AVLNodePointer parent);
    AVLNodePointer lr_rotation(AVLTree<DataType>::AVLNodePointer parent);
    AVLNodePointer rl_rotation(AVLTree<DataType>::AVLNodePointer parent);
    AVLNodePointer balance_tree(AVLTree<DataType>::AVLNodePointer temp);
    AVLNodePointer insertAux(AVLTree<DataType>::AVLNodePointer &subtreeRoot,const DataType &value);
    AVLNodePointer findmin(AVLTree<DataType>::AVLNodePointer temp);
    AVLNodePointer deleteAux(AVLTree<DataType>::AVLNodePointer temp,DataType &value);
    void graphAux(ostream &out,int indent,  AVLTree<DataType>::AVLNodePointer subtreePtr) const;
                            };
template<typename DataType>
int AVLTree<DataType>::height(AVLTree<DataType>::AVLNodePointer temp)
{
     int h=0;
     if(temp!=NULL)
 {
    int left_height=height(temp->left);
    int right_height=height(temp->right)
    int max_height =max(left_height,right_height);
    h=max_height +1;
 }
 return h;
}

template<typename DataType>
int AVLTree<DataType>::different(AVLTree<DataType>::AVLNodePointer temp)
{
int left_height=height(temp->left);
int right_height=height(temp->right);
temp->balanceFactor=left_height-right_height;
return temp->balanceFactor;
}

template<typename DataType>
typename AVLTree<DataType>::AVLNodePointer AVLTree<DataType>::ll_rotation(AVLTree<DataType>::AVLNodePointer parent)
{
AVLTree<DataType>::AVLNodePointer temp;
temp=parent->left;
parent->left=temp->right;
temp->right=parent;
return temp;
}

template<typename DataType>
typename AVLTree<DataType>::AVLNodePointer AVLTree<DataType>::rr_rotation(AVLTree<DataType>::AVLNodePointer parent)
{
AVLTree<DataType>::AVLNodePointer temp;
temp=parent->right;
parent->right=temp->left;
temp->left=parent;
return temp;
}

template<typename DataType>
typename AVLTree<DataType>::AVLNodePointer AVLTree<DataType>::lr_rotation(AVLTree<DataType>::AVLNodePointer parent)
{
AVLTree<DataType>::AVLNodePointer temp;
temp=parent->left;
parent->left=rr_rotation(temp);
return ll_rotation(parent);
}

template<typename DataType>
typename AVLTree<DataType>::AVLNodePointer AVLTree<DataType>::rl_rotation(AVLTree<DataType>::AVLNodePointer parent)
{
AVLTree<DataType>::AVLNodePointer temp;
temp=parent->right;
parent->right=ll_rotation(temp);
return rr_rotation(parent);
}

template<typename DataType>
typename AVLTree<DataType>::AVLNodePointer AVLTree<DataType>::balance_tree(AVLTree<DataType>::AVLNodePointer temp)
{
temp->balanceFactor=different(temp);

if(temp->balanceFactor>1)
{
    if(different(temp->left)>0)
    {
        temp=ll_rotation(temp);
    }
    else
    {
        temp=lr_rotation(temp);
    }
}
else if(temp->balanceFactor<-1)
{
    if(different(temp->right)>0)
    {
        temp=rl_rotation(temp);
    }
    else
    {
        temp=rr_rotation(temp);
    }
}
return temp;  //no balance needed
}

template<typename DataType>
typename AVLTree<DataType>::AVLNodePointer AVLTree<DataType>::findmin(AVLTree<DataType>::AVLNodePointer temp)
{
    if(temp->left==NULL)
    {
        return temp;
    }
    else
    {
        findmin(temp->left);
    }
}
template<typename DataType>
void AVLTree<DataType>::remove(DataType &value)
{
    deleteAux(myRoot,value);
}

template<typename DataType>
typename AVLTree<DataType>::AVLNodePointer AVLTree<DataType>::deleteAux(AVLTree<DataType>::AVLNodePointer temp,DataType &value)
{

if(temp==NULL)
{
    return temp;
}
if (value<temp->data)
{
    temp->left=deleteAux(temp->left,value);
    temp=balance_tree(temp);
}
else if(value>temp->data)
{
    temp->right=deleteAux(temp->right,value);
    temp= balance_tree(temp);
}
else
{
    if(temp->left==NULL && temp->right==NULL)
    {
        AVLTree<DataType>::AVLNodePointer temp1;
        temp1=temp;
        delete temp1;
        temp=NULL;
    }
    else if(temp->left==NULL)
    {
        AVLTree<DataType>::AVLNodePointer temp1=temp;
        temp=temp->right;
        delete temp1;
        temp1=NULL;

    }
    else if(temp->right==NULL)
    {
        AVLTree<DataType>::AVLNodePointer temp1=temp;
        temp=temp->left;
        delete temp1;
        temp1=NULL;

    }
    else
    {
        AVLTree<DataType>::AVLNodePointer temp1=findmin(temp->right);
        temp->data=temp1->data;
        temp->right=deleteAux(temp->right, temp1->data);
    }

}
return temp;
}

只需编辑忘记添加删除功能

Answer 1

您应该尝试使用调试器调试代码以查看正在发生的事情。

跳出来的一件事是你在第一次调用时没有使用deleteAux的返回值，所以如果deleteAux改变了root应该是什么，你就不会拥有正确的root权限值。尝试将remove功能更改为：

myRoot = deleteAux(myRoot,value);

为什么我的AVL树删除功能不平衡？

1 个答案: