[004] last_k_node

[Description] find the k-th node from the last node of single linked list.

e.g.　　Linked-list: 1-2-3-4-5-6-7-8-9

　　　  the last 4th node is: 6

[Thought] using two node point which are separated by k-2 nodes and moving them together.　　O(n)

[Implementation] C code:

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

 // construct single linked list.
 typedef struct node
 {
         int data;
         struct node *next;
 }linklist, *pLL;

 // create a linked list from array.
 pLL createLL(int seq[], int size)
 {
         int i;
         pLL phead,pnode;

         if(size>=)
         {
                 phead=pnode=(pLL)malloc(sizeof(linklist));
                 pnode->next=NULL;
                 pnode->data=seq[];
         }
         else
         {
                 printf("ERROR: No element in array!");
                 return NULL;
         }

         for(i=;i<size;i++)
         {

                 pnode->next=(pLL)malloc(sizeof(linklist));
                 pnode=pnode->next;
                 pnode->next=NULL;
                 pnode->data=seq[i];
         }
         return phead;
 }

 // find the Kth node from the last one.
 int lastKnode(pLL pll,int k)
 {
         linklist *m,*n;
         m=pll;
         int i;

         for(i=;i<k;i++)
         {
                 if(m!=NULL)
                 {
                         m=m->next;
                 }
                 else
                 {
                         printf("ERROR:The length of linklist is less than k!");
                         return -;
                 }
         }
         n=pll;

         while(m->next!=NULL)
         {
                 m=m->next;
                 n=n->next;
         }
         return n->data;
 }

 main()
 {
         int seq[]={,,,,,,,,};
         int size;
         pLL pll;
         pll=NULL;
         size=sizeof(seq)/sizeof(seq[]);
         pll=createLL(seq,size);

         int k=;
         printf("The %dth node from the last is:%d\n",k,lastKnode(pll,k));
 }