C 中的 AVL 旋转

Question

当发生旋转时，只有第一次旋转在我的代码中起作用我不明白为什么我认为旋转功能 return 错误的节点？可能是。下面是我的节点和树结构

#define ll unsigned long
typedef struct NODE_s *NODE; //Node structure
typedef struct NODE_s{
    NODE right,left;
    ll key;
    int height;
    void *data;
} NODE_t[1];

typedef struct AVL_s *AVL; //Tree structure
typedef struct AVL_s{
    NODE root;
} AVL_t[1];

初始化函数

AVL AVL_init(){
    AVL t = (AVL)malloc(sizeof(AVL_t));
    t->root = NULL;
    return t;
}
NODE node_init(ll init_key){
    NODE node = (NODE)malloc(sizeof(NODE_t));
    node->left = NULL;
    node->right = NULL;
    node->key = init_key;
    node->height = 1;
    node->data = NULL;
    return node;
}

旋转函数

NODE rightRotate(NODE node){

    NODE child  = node->left;
    NODE childR = child->right;

    child->right = node;
    node->left = childR;


        node->height = max(height(node->left), height(node->right))+1;
        child->height = max(height(child->left), height(child->right))+1;

    return child;
}
NODE leftRotate(NODE node)
{
    NODE child  = node->right;
    NODE childL = child->left;

    child->left = node;
    node->right = childL;


        node->height = max(height(node->left), height(node->right))+1;
        child->height = max(height(child->left), height(child->right))+1;

        return child;
}

递归插入我认为必须使用两个函数从 main 发送树，然后在插入函数中使用 tree->root。

NODE insert_rec(NODE node,ll rec_key){
    if(rec_key < node->key){
        if(node->left == NULL)
            node->left = node_init(rec_key);
        else
            insert_rec(node->left, rec_key);
    }else if(rec_key > node->key){
        if(node->right == NULL)
            node->right = node_init(rec_key);
        else
            insert_rec(node->right, rec_key);
    }else
        printf("Duplicate %lu Data\n",rec_key);

    //If I delete from here to end of functions, it is clearly recursive BST insert and works successfully

    node->height = 1 + max(height(node->left),height(node->right));
    int balanceFactor = balance(node);

    if (balanceFactor > 1 && rec_key < node->left->key) //leftleft
       node = rightRotate(node);   //return rightRotate(node) also working

    if (balanceFactor < -1 && rec_key > node->right->key) //rightright
        node = leftRotate(node);   //return leftRotate(node) also working

    if (balanceFactor > 1 && rec_key > node->left->key) //leftright
    {
        node->left =  leftRotate(node->left);
        node = rightRotate(node); 
    }
    if (balanceFactor < -1 && rec_key < node->right->key) //rightright
    {
        node->right = rightRotate(node->right);
        node = leftRotate(node);
    }
   return node;
}
void insert(AVL tree,ll key){
    if(key == -1){
        printf("Invalid data %lu\n",key);
    }
    else if(tree->root == NULL){
        tree->root = node_init(key);
    }
    else{
       tree->root = insert_rec(tree->root,key);
    }
}

int main() {
    AVL tree = AVL_init();
    insert(tree,111);
    }

这是我的源代码，我无法理解我没有看到的内容。如果我更换它正常的 BST 它正在工作但是当旋转发生时节点出现在某处

Answer 1

我解决了。函数 insert() 变成垃圾并将其放入 insert_rec()。它只是根检查 if root = null 条件。

然后main函数就这样替换了，

int main() {
    AVL tree = AVL_init();
    NODE node = tree->root;
    insert_rec(node,111);
}

最后，在平衡因素的情况下，我只需要return函数

return leftRotate(node); //instead of node = leftRotate(node);

return rightRotate(node); //instead of node = rightRotate(node);

这种观点使得处理return来自函数的值变得容易

C 中的 AVL 旋转

AVL rotations in C

c

avl-tree

recursive-datastructures