[002] delete_duplication_of_linked_list

[Description] Given a unsort linked list, delete all the duplication from them, no temporary space permission.

[Thought] Set two points, from head to tail, scaning all linked list. O(n^2).

[Implementation] C code:

 #include<stdio.h>

 typedef struct linkedList
 {
         int data;
         struct linkedList* next;
 } llist;

 llist** delDupli(llist **head)
 {
         // two point, t1 for target, t2 for mover.
         llist *t1, *t2;
         t1=t2=*head;
         while(t1->next != NULL)
         {
                 // ajust t2 from t1!
                 t2=t1;
                 while(t2->next != NULL)
                 {
                         // check if they are the same
                         if(t2->next->data == t1->data)
                         {
                                 // move t2->next; note: no memory free here.
                                 t2->next=t2->next->next;
                         }
                         // after move out node, check if t2 is already the last one.
                         if(t2->next != NULL)
                         {
                                 t2=t2->next;
                         }
                 }
                 t1=t1->next;
         }
         return head;
 }

 int addValue(llist **head, int val)
 {

         llist *pnode;
         llist *t=*head;
         // apply memory for linked list.
         pnode=(llist*)malloc(sizeof(llist));
         if(NULL==pnode)
         {
                 return ;
         }
         pnode->data=val;
         pnode->next=NULL;
         // first node
         if(NULL==*head)
         {
                 *head=pnode;
                 return ;
         }
         // move temp point to the last node
         while(t->next != NULL)
         {
                 t=t->next;
         }
         t->next=pnode;
         return ;
 }

 // out put data, be careful about the first node.
 int printList(llist **head)
 {
         llist *t=*head;
         printf("%d, ",t->data);
         while(t->next != NULL)
         {
                 t=t->next;
                 printf("%d, ",t->data);
         }
         printf("\n");
         return ;
 }

 int main()
 {
         int a[]={,,,,,,,,,,,,};
         llist *head=NULL;
         int i;

         for(i=;i<(sizeof(a)/sizeof(a[]));i++)
         {
 //              printf("a[i]:%d\n",a[i]);
                 addValue(&head,a[i]);
 //              printList(&head);
         }
         printf("Initial linked list:\n");
         printList(&head);
         printf("After deleting:\n");
         printList(delDupli(&head));
 }