从具有特定值的链接列表中删除节点

Question

我正在编写一个程序，该程序具有需要根据其值删除节点的功能。

我已经试过并试图弄清楚。

所有我至今是函数签名：

NODE* delete_node(NODE * ptr, int n, int *success_flag) 

我的链表后续的结构：

/* declaration of structure */ 
typedef struct node 
{ 
    int data; 
    struct node *next; 
} NODE; 

继承人一些代码，我已经有关于另一个担忧：

#include <stdio.h> 
#include <stdlib.h> 

/* declaration of structure */ 
typedef struct node 
{ 
    int data; 
    struct node *next; 
} NODE; 

/* declaration of functions */ 
NODE* insert_node(NODE *ptr, NODE *new); 
NODE* find_node(NODE *ptr, int n); 
NODE* delete_node(NODE *ptr, int n, int *success_flag_ptr); 
void print_backward_iteration(NODE *ptr); 
void print_backward_recursion(NODE *ptr); 

int main(int argc, char *argv[]) 
{ 
    int choice, x, flag_success; 
    NODE *ptr, *new, *result; 

    ptr = NULL; 

    do 
    { 

     printf("\n1.\tInsert Integer into linked list\n"); 
     printf("2.\tFind integer in linked list\n"); 
     printf("3.\tDelete integer from linked list\n"); 
     printf("4.\tPrint out integers backward using the iterative strategy\n"); 
     printf("5.\tPrint out integers backward using the recursive strategy\n"); 
     printf("6.\tQuit\n"); 
     printf("\nEnter 1,2,3,4,5, or 6: "); 
     scanf("%d", &choice); 

     switch(choice) 
    { 
    case 1: 

     printf("\nPlease enter an integer: "); 
     scanf("%d", &x); 
     new = (NODE *)malloc(sizeof(NODE)); 
     new->data = x; 
     ptr = insert_node(ptr, new); 
     printf("\nNode Inserted with value of %d.\n", ptr->data); 
     break; 

    case 2: 

     printf("\nPlease enter an integer: "); 
     scanf("%d", &x); 
     result = find_node(ptr, x); 

     if (result == NULL) 
     { 
      printf("\nValue could not be found.\n"); 
     } 
     else 
     { 
      printf("\nValue %d was found.\n", x); 
     } 

     break; 

    case 3: 
     printf("\nPlease enter an integer: "); 
     scanf("%d", &x); 
     ptr = delete_node(ptr, x, &flag_success); 

     if (result == NULL) 
     { 
      printf("\nValue could not be found.\n"); 
     } 
     else 
     { 
      printf("\nValue %d was deleted.\n", x); 
     } 

     break; 

    case 4: 

     print_backward_iteration(ptr); 
     break; 

    case 5: 

     printf("\n"); 
     print_backward_recursion(ptr); 
     printf("\n"); 

     break; 

    case 6: 
     printf("\nThank you for using this program.\n"); 
    break; 

    default: 
     printf("\nInvalid Choice. Please try again.\n"); 
     break; 

    } 
    } 
    while (choice != 6); 

    printf("\n*** End of Program ***\n"); 
    return 0; 
} 

/* definition of function insert_node */ 
NODE* insert_node(NODE *ptr, NODE *new) 
{ 

new -> next = ptr; 
return new; 

} 

/* definition of function find_node */ 
NODE* find_node(NODE *ptr, int n) 
{ 

    while (ptr != NULL) 
    { 
     if (ptr->data == n) 
    { 
     return ptr; 
    } 
     else 
    { 
     ptr = ptr->next; 
    } 
    } 
    return NULL; 
    } 

/* definition of function print_backward_iteration */ 
void print_backward_iteration(NODE *ptr) 
{ 
    NODE *last, *current; 

    last = NULL; 

    printf("\n"); 

    while (ptr != last) 
    { 
     current = ptr; 

     while (current != last) 
    { 
     current = current -> next; 
    } 

     printf("%d ", current -> data); 
     last = current -> next; 
    } 

    printf("\n"); 

} 

/* definition of function print_backward_recursion */ 
void print_backward_recursion(NODE *ptr) 
{ 
    NODE *last, *current; 

    last = NULL; 

    while (ptr != last) 
     { 
    current = ptr; 
    printf("%d ", current -> data); 
    print_backward_recursion(current -> next); 
    last = current; 
     } 

} 

Answer 1

你必须这样做：

NODE* delete_node(NODE * ptr, int n, int *success_flag) 
{ 
    Node *aux = NULL; 

    if(ptr == NULL) // this means that theres is no 'n' in this linked list 
    { 
    *success_flag = 0; // means no value found 
    return NULL; 
    } 
    if(ptr-> n == n){  // if this is the value you want 
     aux = ptr->next; // aux will point to the remaining list 
     free(ptr);   // free the actual node 
     *success_flag = 1; // mark as success 
     return aux;  // return the pointer to the remaining list 
    } 
    else // lets see the remaining nodes 
     ptr->next = delete_node(ptr->next,n,success_flag); 

    return ptr; 
}