用于从链接列表中删除最后一次出现的项目的 C 程序

用于从链接列表中删除项目的最后一次出现的 C 程序

使用指针，遍历整个列表并使用特殊指针跟踪包含最后出现键的节点之前的节点。在此之后，只需将下一个特殊指针的下一个存储到特殊指针的下一个中，以从链表中删除所需的节点。

C

#include 
#include 
  
// A linked list Node
struct Node 
{
    int data;
    struct Node* next;
};
  
// Function to delete the last 
// occurrence
void deleteLast(struct Node** head, 
                int x)
{
    struct Node** tmp1 = NULL;
    while(*head) 
    {
        if((*head)->data == x) 
        {
            tmp1 = head;
        }
        head = &(*head)->next;
    }
    if(tmp1) 
    {
        struct Node* tmp = *tmp1;
        *tmp1 = tmp->next;
        free(tmp);
    }
}
  
/* Utility function to create a 
   new node with given key */
struct Node* newNode(int x)
{
    struct Node* node = 
           malloc(sizeof(struct Node*));
    node->data = x;
    node->next = NULL;
    return node;
}
  
// This function prints contents of 
// linked list starting from the given
// Node
void display(struct Node* head)
{
    struct Node* temp = head;
    if (head == NULL) 
    {
        printf("NULL");
        return;
    }
    while (temp != NULL) 
    {
        printf("%d --> ", 
                temp->data);
        temp = temp->next;
    }
    printf("NULL");
}
  
// Driver code
int main()
{
    struct Node* head = newNode(1);
    head->next = newNode(2);
    head->next->next = 
    newNode(3);
    head->next->next->next = 
    newNode(4);
    head->next->next->next->next = 
    newNode(5);
    head->next->next->next->next->next = 
    newNode(4);
    head->next->next->next->next->next->next = 
    newNode(4);
    printf("Created Linked list: ");
    display(head);
  
    // Pass the address of the head pointer
    deleteLast(&head, 4);   
    printf("List after deletion of 4: ");
    display(head);
    return 0;
}

输出：

Created Linked list: 1 --> 2 --> 3 --> 4 --> 5 --> 4 --> 4 --> NULL
List after deletion of 4: 1 --> 2 --> 3 --> 4 --> 5 --> 4 --> NULL

当要删除的节点是最后一个节点时，上述解决方案不起作用。
以下解决方案处理所有情况。

C

// A C program to demonstrate deletion 
// of last Node in singly linked list
#include 
#include 
  
// A linked list Node
struct Node 
{
    int data;
    struct Node* next;
};
  
// Function to delete the last 
// occurrence
void deleteLast(struct Node* head, 
                int x)
{
    struct Node *temp = head, 
                *ptr = NULL;
    while (temp) 
    {
        // If found key, update
        if (temp->data == x) 
            ptr = temp;        
        temp = temp->next;
    }
  
    // If the last occurrence is the 
    // last node
    if (ptr != NULL && 
        ptr->next == NULL) 
    {
        temp = head;
        while (temp->next != ptr) 
            temp = temp->next;       
        temp->next = NULL;
    }
  
    // If it is not the last node
    if (ptr != NULL && 
        ptr->next != NULL) 
    {
        ptr->data = ptr->next->data;
        temp = ptr->next;
        ptr->next = ptr->next->next;
        free(temp);
    }
}
  
/* Utility function to create a 
   new node with given key */
struct Node* newNode(int x)
{
    struct Node* node = 
           malloc(sizeof(struct Node*));
    node->data = x;
    node->next = NULL;
    return node;
}
  
// This function prints contents of 
// linked list starting from the given 
// Node
void display(struct Node* head)
{
    struct Node* temp = head;
    if (head == NULL) 
    {
        printf("NULL");
        return;
    }
    while (temp != NULL) 
    {
        printf("%d --> ", temp->data);
        temp = temp->next;
    }
    printf("NULL");
}
  
// Driver code
int main()
{
    struct Node* head = newNode(1);
    head->next = newNode(2);
    head->next->next = newNode(3);
    head->next->next->next = 
    newNode(4);
    head->next->next->next->next = 
    newNode(5);
    head->next->next->next->next->next = 
    newNode(4);
    head->next->next->next->next->next->next = 
    newNode(4);
    printf("Created Linked list: ");
    display(head);
    deleteLast(head, 4);
    printf("List after deletion of 4: ");
    display(head);
    return 0;
}

输出：

Created Linked List: 
1  2  3  4  5  4  4 
Linked List after Deletion of 1: 
1  2  3  4  5  4

有关详细信息，请参阅有关从链接列表中删除最后一个项目的完整文章！