C示例在圆形链接列表中查找项目的程序

#include <stdio.h>

#include <stdlib.h>



struct node {

   int data;

   struct node *next;

};



struct node *head = NULL;

struct node *current = NULL;



//insert link at the first location

void insert(int data) {

   // Allocate memory for new node;

   struct node *link = (struct node*) malloc(sizeof(struct node));



   link->data = data;

   link->next = NULL;



   // If head is empty, create new list

   if(head==NULL) {

      head = link;

      head->next = link;

      return;

   }



   current = head;



   // move to the end of the list

   while(current->next != head)

      current = current->next;



   // Insert link at the end of the list

   current->next = link;



   // Link the last node back to head

   link->next = head;



}



//display the list

void find_data(int item) {

   int pos = 0;



   if(head == NULL) {

      printf("Linked List not initialized");

      return;

   }



   current = head;



   while(current->next != head) {

      if(current->data == item) {

         printf("%d found at position %d\n", item, pos);

         return;

      }



      current = current->next;

      pos++;

   }



   if(current->data == item) {

      printf("%d found at position %d\n", item, pos);

      return;

   }



   printf("%d does not exist in the list", item);

}



int main() {

   insert(10);

   insert(20);

   insert(30);

   insert(1);

   insert(40);

   insert(56);



   find_data(56);



   return 0;

}