Question

我试图为练习实现一个简单的二进制搜索树。我试图只添加值并在节点中打印值。但是，我没有在节点中获得正确的值升序。这就是我所拥有的：

struct Node
{
    int data;
    Node* leftN;
    Node* rightN;

};

typedef Node* Node_ptr;
Node_ptr head;

//INSERT_VALUE FUNCTION
Node* insert_value(Node_ptr leaf, int key)
{
    //Root case when there is no set value yet  
    if(leaf == NULL)
    {
        leaf = new Node;
        head = leaf;
        cout << "Make the first node" << endl;
        leaf->data = key;
        leaf->leftN = NULL;
        leaf->rightN = NULL;
        return leaf;
    }   
    //Left child Node
    if(key < leaf->data)
    {
        //Search for a spot in the tree to add a Node (left value < root value < right value)
        //This is only true for the left child Node
        if(leaf->leftN != NULL)
            insert_value(leaf, key);
        //We have found a spot in the tree to add a new Node and add the value of key
        else 
        {
            cout << "Insert-left" << endl;
            leaf->leftN = new Node;
            leaf = leaf->leftN;
            leaf->data = key;
            leaf->leftN = NULL;
            leaf->rightN = NULL;
            return leaf;
        }
    }

    //Right child Node
    else if(key >= leaf->data)
    {
        //Search for a spot to add a new Node in the tree (only amongst the right child Nodes)
        if(leaf->rightN != NULL)
            insert_value(leaf, key);    
        //Once we have found a spot to add a new Node, append the new Node
        else
        {
            cout << "Insert-right" << endl;
            leaf->rightN = new Node;
            leaf = leaf->rightN;    
            leaf->data = key;
            leaf->leftN = NULL;
            leaf->rightN = NULL;
            return leaf;
        }
    }   
}

//PRINT FUNCTION
void printTree(Node_ptr leaf)
{
    if(leaf == NULL)
        return;
    printTree(leaf->leftN);
    cout << "Data element: " << leaf->data << endl;
    printTree(leaf->rightN);
}

//MAIN
int main()
{
    Node_ptr root = NULL;
    int i;

    //initialize values
    for(i = 1; i < 12; i+=2)
        root = insert_value(root, i);
    root = head;
    for(i = 0; i < 11; i+=2)
        root = insert_value(root, i);
    root = head;
    printTree(root);

    root = head;
    cout << "Head Node: " << root->data << endl;

    return 0;
}

当我打印结果时，这就是我得到的： 0,2,4,6,8,10,1,3,5,7,9,11和头节点的值是1

Answer 1

因为您将插入称为：

    root = insert_value(root, i);

您插入的位置始终使用从上次插入开始的子树。除了重新开始添加奇数的时间，当你开始插入头部时。

如果你创建一个包含头指针的class BinarySearchTree，以及一个调用int value的{{1}}的insert方法，那么你可以只调用该类的insert，而不传递它一个节点，它总是可以看到插入使用树的根来开始递归。

只是我，但我会为Node创建一个构造函数，它接受Node::insert( head, value )并将指针初始化为NULL。这样你就不必在insert方法中这样做了。

Answer 2

在leaf-＆gt;节点？！= NULL情况，我认为不是调用

insert_value(leaf, key);

你想说

leaf->node? = insert_value(leaf->node?, key)

在哪里？当然是L或R.

您可能会考虑的是向方法添加注释，如下所示：

// Adds the given key to the (sub-)tree rooted at node* then returns the new root
// of that (sub-)tree.
node *insert_value_and_return_root(node *root, int value) { ... }

二进制搜索树C ++

2 个答案: