专家,这是我在Binary Search Tree中创建和删除节点的代码。它可以很好地插入,但是在尝试删除节点时(调用deleteNode()函数)会抛出分段错误(核心已转储)。我不明白实际上是什么问题。
请帮忙!预先谢谢你!
#include <stdio.h>
#include <stdlib.h>
int size = 0;
typedef struct mylist{
int data;
struct mylist *left;
struct mylist *right;
}node;
node *root;
void create_root(node *root){
root = NULL;
}
//Inserting nodes
node* insert(node *root, int val){
node *ptr, *parentptr, *nodeptr;
ptr = (node*)malloc(sizeof(node));
ptr -> data = val;
ptr -> left = NULL;
ptr -> right = NULL;
if(root == NULL)
root = ptr;
else{
parentptr = NULL;
nodeptr = root;
while(nodeptr != NULL){
parentptr=nodeptr;
if(val < nodeptr -> data)
nodeptr = nodeptr -> left;
else
nodeptr = nodeptr -> right;
}
if(val < parentptr -> data)
parentptr -> left = ptr;
else
parentptr -> right = ptr;
}
return root;
}
node* minValueNode(node* root)
{
node* cur = root;
while (cur->left != NULL)
cur = cur->left;
return cur;
}
node* deleteNode(node* root, int key)
{
if (root == NULL){
printf("\nValue not found\n");
}
if (key < root-> data)
root->left = deleteNode(root->left, key);
else if (key > root-> data)
root->right = deleteNode(root->right, key);
else
{
if (root->left == NULL)
{
node *temp = root->right;
free(root);
return temp;
}
else if (root->right == NULL)
{
node *temp = root->left;
free(root);
return temp;
}
node* temp = minValueNode(root->right); //Inorder successor
root->data = temp->data;
root->right = deleteNode(root->right, temp->data);
}
return root;
}
void main(){
int option, val;
node *ptr;
int flag = 1;
create_root(root);
while(flag != 2){
printf("\nChoose-\n1-Insert\n2-Delete\n3-Exit\n");
scanf("%d", &option);
switch(option){
case 1:{
printf("\nEnter the value of new node\n");
size++;
scanf("%d", &val);
root = insert(root, val);
break;
}
case 2:{
int k;
printf("Enter the value to delete");
scanf("%d",&k);
root=deleteNode(root, k);
size--;
break;
}
case 3:
flag=2;
break;
default:
printf("\nWrong entry\n");
}
}
}
答案 0 :(得分:1)
您必须在NULL
的第一个if()
中返回deleteNode()
,或者必须在第二个else
之前放置一个if()
node* deleteNode(node* root, int key)
{
if (root == NULL){
printf("\nValue not found\n");
return NULL; // <== This was missing.
}
...
}
或替代(也许是故意的?):
node* deleteNode(node* root, int key)
{
if (root == NULL){
printf("\nValue not found\n");
}
else if(key < root->data)
...
}
此刻,即使if(key < root->data)
为空,它也会进入下一个root
,这会导致段错误。
也:如果可以使用C ++ 11,请使用nullptr
。