Question

我正在尝试在节点所在的AVL树中添加数字（键，值）。在for循环中输入从（0,0）到（10,10）的数字时，代码在尝试输入数字（10,10）时失败。

以下是将节点插入树中的代码：

int insert_in_tree_q5(struct AVLTreeNode **node, int key, int value){

    //AVLTreeNode *newNode = newAVLTreeNode(key, value);
    // if the tree is empty
    if(*node == NULL){
        *node = newAVLTreeNode(key, value);
    }
    if(key != (*node)->key){
        // insert on left if the data in the key is less than the data in the node.
        if (key<(*node)->key){
            insert_in_tree_q5(&(*node)->left, key,value);
        }
        // insert on right if the data in the key is greater than the data in the node.
        else if(key>(*node)->key)
        {
            insert_in_tree_q5(&(*node)->right, key,value);
        }
        // Update height of the ancestor node
        (*node)->height = 1 + max(height((*node)->left), height((*node)->right));
        // check balance to see if this node became unbalanced
        int balance = getBalance(*node);

        //First case to balance the unbalanced node
        // Left Left case
        if(balance>1 && key<(*node)->left->key){
            *node = rightRotate(*node);
        }
        // Right Right Case
        if (balance < -1 && key > (*node)->right->key)
            *node = leftRotate(*node);

        // Left Right Case
        if (balance > 1 && key > (*node)->left->key)
        {
            (*node)->left =  leftRotate((*node)->left);
            *node = rightRotate(*node);
        }

        // Right Left Case
        if (balance < -1 && key < (*node)->right->key)
        {
            (*node)->right = rightRotate((*node)->right);
            *node = leftRotate(*node);
        }
    }
    else if(key == (*node)->key){
        if (value<(*node)->value){
            insert_in_tree_q5(&(*node)->left, key,value);
        }
        // insert on right if the data in the key is greater than the data in the node.
        else if(value>(*node)->value)
        {
            insert_in_tree_q5(&(*node)->right, key,value);
        }
        // Update height of the ancestor node
        (*node)->height = 1 + max(height((*node)->left), height((*node)->right));
        // check balance to see if this node became unbalanced
        int balance = getBalance(*node);

        //First case to balance the unbalanced node
        // Left Left case
        if(balance>1 && value<(*node)->left->value){
            *node =rightRotate(*node);
        }
        // Right Right Case
        if (balance < -1 && value > (*node)->right->value)
            *node =leftRotate(*node);

        // Left Right Case
        if (balance > 1 && value > (*node)->left->value)
        {
            (*node)->left =  leftRotate((*node)->left);
            *node =rightRotate(*node);
        }

        // Right Left Case
        if (balance < -1 && value < (*node)->right->value)
        {
            (*node)->right = rightRotate((*node)->right);
            *node =leftRotate(*node);
        }
    }else if(key == (*node)->key && value == (*node)->value){
        return 0;
    }
    return 1;

}

“向左旋转”的代码是：

struct AVLTreeNode* leftRotate(struct AVLTreeNode *x){
    struct AVLTreeNode *y = x->right;
    struct AVLTreeNode *T2 = y->left;

    // Perform rotation
    y->left = x;
    x->right = T2;

    //  Update heights
    x->height = max(height(x->left), height(x->right))+1;
    y->height = max(height(y->left), height(y->right))+1;

    // Return new root
    return y;
}

我在树中输入值的方式是：

int InsertNode(AVLTree *T, int k, int v)
{
    //put your code here
    int returnedValue = insert_in_tree_q5(&T->root, k, v);
    if(returnedValue==0){
        return 0;
    }
    return 1;
}
tree4=newAVLTree();
    j=InsertNode(tree4, 10, 10);
    for (i=0; i<15; i++)
    {
        j=InsertNode(tree4, i, i);
        if (j==0) printf("(%d, %d) already exists\n", i, i);
    }

AVLTreeNode和AVLTree的签名为：

typedef struct AVLTreeNode {
    int key; //key of this item
    int  value;  //value (int) of this item
    int height; //height of the subtree rooted at this node
    struct AVLTreeNode *parent; //pointer to parent
    struct AVLTreeNode *left; //pointer to left child
    struct AVLTreeNode *right; //pointer to right child
} AVLTreeNode;

AVLTree *newAVLTree()
{
    AVLTree *T;
    T = malloc(sizeof (AVLTree));
    assert (T != NULL);
    T->size = 0;
    T->root = NULL;
    return T;
}

PS：如果（k，v）项已经存在，则应返回0，否则将其添加到树中并返回1。关于为什么它接受直到（9,9）的所有值但在（10,10）失败并出现错误“线程1：EXC_BAD_ACCESS（code = 1，address = 0x18）”的任何想法

Answer 1

如果（k，v）项已经存在，则应返回0，否则将其添加到树中并返回1

在insert_in_tree_q5中，您可以这样做：

if(*node == NULL){
    *node = newAVLTreeNode(key, value);
}
if(key != (*node)->key){
  ...CASE A
}
else if(key == (*node)->key){
    ...CASE B
} else if(key == (*node)->key && value == (*node)->value){
    return 0;
}
return 1;

else if(key == (*node)->key && value == (*node)->value)永远无法到达的情况是因为在执行else if(key == (*node)->key)之前，您需要颠倒顺序。

对我来说，(*node == NULL)时您也不必继续

请注意，您已经知道if(key != (*node)->key)是错误的，因此在接下来的两个测试中测试相等性是没有用的

最后，您的代码必须是：

if(*node == NULL){
    *node = newAVLTreeNode(key, value);
}
else if(key != (*node)->key){
  ...CASE A
}
else if( value == (*node)->value){
    return 0;
}
else {
    ...CASE B
} 
return 1;

在

int InsertNode(AVLTree *T, int k, int v)
{
    //put your code here
    int returnedValue = insert_in_tree_q5(&T->root, k, v);
    if(returnedValue==0){
        return 0;
    }
    return 1;
}

因为insert_in_tree_q5仅返回0或1，所以 InsertNode 可以简化为

int InsertNode(AVLTree *T, int k, int v)
{
    return insert_in_tree_q5(&T->root, k, v);
}

输入1-10

1 个答案: