所以我在C中使用二进制搜索树的代码对我来说很好。但是，当我为BST删除添加代码时，我的程序将在删除期间崩溃。
它给我一个错误，说 访问冲突读取位置0x00000000。
我认为这与传递NULL指针或其他东西有关。也许我在某个地方看过，或者说这完全错了，我很傻。
无论如何，这是我的AVL删除代码。如果你能帮助我让我的计划工作并帮助我理解我做错了什么，我将非常感激。我还会包含我找到最小节点的功能，因为我觉得它可能是罪魁祸首。
AVL min_node(AVL self)
{
/* A AVL node to keep track of the current node. */
AVL current = self;
/* This loop finds the minimum node, by traversing the tree until the leftmost node is discovered. */
while (!empty_tree(current))
{
current = current->left;
}
/* Returns the tree. */
return current;
}
AVL delete(AVL self, long id)
{
if (self != NULL)
{
if (id == self->student_id)
{
if (self->left != NULL)
{
AVL successor = min_node(self->right);
self->student_id = successor->student_id;
self->right = delete(self->right, self->student_id);
}
else
{
AVL to_free = self;
if (self->left)
{
self = self->left;
}
else
{
self = self->right;
}
free(to_free);
}
}
else if (id < self->student_id)
{
self->left = delete(self->left, id);
}
else
{
self->right = delete(self->right, id);
}
}
/*NEW SHIT*/
int balance = getBalance(self);
//Left Left Case
if (balance > 1 && getBalance(self->left) >= 0)
{
return rotateRight(self);
}
//Left Right Case
if (balance > 1 && getBalance(self->left) < 0)
{
self->left = leftRotate(self->left);
return rotateRight(self);
}
//Right Right Case
if (balance < -1 && getBalance(self->right) <= 0)
{
return leftRotate(self);
}
//Right Left Case
if (balance < -1 && getBalance(self->right) > 0)
{
self->right = rotateRight(self->right);
return leftRotate(self);
}
return self;
}
UPDATE：所以它似乎在删除功能中的两行之一崩溃：
self->student_id = successor->student_id;
OR
AVL successor = min_node(self->right);
编辑2：根据要求，我已经包含了我的整个avl.c文件。
#include <stdlib.h>
#include <stdbool.h>
#include "avl.h"
bool names_match(char* name_one, char* name_two)
{
if (strcmp(name_one, name_two) == 0)
{
return true;
}
else
{
return false;
}
}
bool empty_tree(AVL self)
{
if (self == NULL)
{
return true;
}
else
{
return false;
}
}
AVL leftRotate(AVL self)
{
AVL y = self->right;
AVL T2 = y->left;
y->left = self;
self->right = T2;
return y;
}
AVL rotateRight(AVL self)
{
AVL x = self->left;
AVL T2 = x->right;
x->right = self;
self->left = T2;
return x;
}
int getBalance(AVL node)
{
if (node == NULL)
{
return 0;
}
return height(node->left) - height(node->right);
}
AVL insert(AVL self, long id)
{
if (self == NULL)
{
self = (AVL)malloc(sizeof(struct avlNode));
self->student_id = id;
self->left = self->right = NULL;
}
else if (id < self->student_id)
{
self->left = insert(self->left, id);
}
else if (id > self->student_id)
{
self->right = insert(self->right, id);
}
/*NEW SHIT*/
int balance = getBalance(self);
//Left Left Case
if (balance > 1 && id < self->left->student_id)
{
return rotateRight(self);
}
//Right Right Case
if (balance < -1 && id > self->right->student_id)
{
return leftRotate(self);
}
//Left Right Case
if (balance > 1 && id > self->left->student_id)
{
self->left = leftRotate(self->left);
return rotateRight(self);
}
//Right Left Case
if (balance < -1 && id < self->right->student_id)
{
self->right = rotateRight(self->right);
return leftRotate(self);
}
//Return unchanged pointer (i dunno why. could probably be void)
return self;
}
/* === AVL MINIMUM NODE ===
Finds the minimum node in a AVL.
*/
AVL min_node(AVL self)
{
/* A AVL node to keep track of the current node. */
AVL current = self;
/* This loop finds the minimum node, by traversing the tree until the leftmost node is discovered. */
while (!empty_tree(current->left))
{
current = current->left;
}
/* Returns the tree. */
return current;
}
AVL delete(AVL self, long id)
{
if (self != NULL)
{
if (id == self->student_id)
{
if (self->left != NULL)
{
AVL successor = min_node(self->right);
self->student_id = successor->student_id;
self->right = delete(self->right, self->student_id);
}
else
{
AVL to_free = self;
if (self->left)
{
self = self->left;
}
else
{
self = self->right;
}
free(to_free);
}
}
else if (id < self->student_id)
{
self->left = delete(self->left, id);
}
else
{
self->right = delete(self->right, id);
}
}
/*NEW SHIT*/
if (self == NULL)
{
return self; //ADDED TODAY
}
int balance = getBalance(self);
//Left Left Case
if (balance > 1 && getBalance(self->left) >= 0)
{
return rotateRight(self);
}
//Left Right Case
if (balance > 1 && getBalance(self->left) < 0)
{
self->left = leftRotate(self->left);
return rotateRight(self);
}
//Right Right Case
if (balance < -1 && getBalance(self->right) <= 0)
{
return leftRotate(self);
}
//Right Left Case
if (balance < -1 && getBalance(self->right) > 0)
{
self->right = rotateRight(self->right);
return leftRotate(self);
}
return self;
}
/* === AVL NODE COUNT ===
Counts the number of nodes in the AVL.
*/
int number_of_nodes(AVL self)
{
/* If the tree is empty, return a count of 0 nodes. */
if (empty_tree(self))
{
return(0);
}
/* If the tree is not empty, but its left and right nodes are, return a count of 1 node. */
else if (empty_tree(self->left) && empty_tree(self->right))
{
return(1);
}
/* If the tree is not empty, and its left and right nodes are also not empty, run this function recursively in the left and right nodes. */
else
{
return(1 + (number_of_nodes(self->left) + number_of_nodes(self->right)));
}
}
/* === AVL HEIGHT ===
Returns the total height of a AVL.
*/
int height(AVL self)
{
/* If the tree is empty, return a count of 0 nodes. */
if (empty_tree(self))
{
return 0;
}
/* If the tree is not empty, run this fucntion recursively on the left and right branches, returning the max of the two. */
else
{
return 1 + max(height(self->left), height(self->right));
}
}
/* === PRINT AVL ===
Prints a AVL in pre-order.
*/
void print_pre_order(AVL self)
{
/* If the tree isn't empty, print the node's ID and then run this function recursively on the left and then the right nodes,
to print pre order. */
if (!empty_tree(self))
{
printf("%d", self->student_id);
printf("\n");
print_pre_order(self->left);
print_pre_order(self->right);
}
}
/* === SEARCH AVL ===
Searches a AVL for a particular node.
*/
bool searchTree(AVL self, long id)
{
if (!empty_tree(self))
{
/* If the node's ID matches the input ID, return true. */
if (self->student_id == id)
{
return true;
}
/* If the node's ID doesn't match the input ID, run this function recurseively on the appropriate node. */
else
{
if (self->student_id > id)
{
return searchTree(self->left, id);
}
else if (self->student_id < id)
{
return searchTree(self->right, id);
}
}
}
return false;
}
void destroy_tree(AVL self)
{
/* If the tree is not empty, free each node in the tree by running this function recursively on the left and right branches. */
if (!empty_tree(self))
{
destroy_tree(self->left);
destroy_tree(self->right);
free(self);
}
}
编辑3：有趣的发展。正在使用的AVL树实际上在链表中，每个节点包含一个AVL树。现在我已经意识到（通过大量测试）可以删除AVL树上的节点， IF 它是第一个被构建的节点。非常有趣，甚至更烦人。
答案 0 :(得分：0)
我认为问题出在＆＃39; self-＆gt; right＆＃39;你传递给函数。如果＆＃39; self＆＃39;是一个指针，我假设它是在我看来你应该通过＆＃39;地址＆＃39;自我＆＃39;像这样＆＃39;＆amp;（自我＆gt;右）＆＃39;并且应该为电流分配“＆＃39;＆amp; self＆＃39;像这样＆＃39; current = * self＆＃39;。然后我认为它可以工作。 我想如果我提供完整的代码，我可以纠正我说的话，但我认为你得到了要点