[004] last_k_node

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 
 4 // construct single linked list.
 5 typedef struct node
 6 {
 7         int data;
 8         struct node *next;
 9 }linklist, *pLL;
10 
11 // create a linked list from array.
12 pLL createLL(int seq[], int size)
13 {
14         int i;
15         pLL phead,pnode;
16 
17         if(size>=1)
18         {
19                 phead=pnode=(pLL)malloc(sizeof(linklist));
20                 pnode->next=NULL;
21                 pnode->data=seq[0];
22         }
23         else
24         {
25                 printf("ERROR: No element in array!");
26                 return NULL;
27         }
28 
29         for(i=1;i<size;i++)
30         {
31 
32                 pnode->next=(pLL)malloc(sizeof(linklist));
33                 pnode=pnode->next;
34                 pnode->next=NULL;
35                 pnode->data=seq[i];
36         }
37         return phead;
38 }
39 
40 // find the Kth node from the last one.
41 int lastKnode(pLL pll,int k)
42 {
43         linklist *m,*n;
44         m=pll;
45         int i;
46 
47         for(i=1;i<k;i++)
48         {
49                 if(m!=NULL)
50                 {
51                         m=m->next;
52                 }
53                 else
54                 {
55                         printf("ERROR:The length of linklist is less than k!");
56                         return -1;
57                 }
58         }
59         n=pll;
60 
61         while(m->next!=NULL)
62         {
63                 m=m->next;
64                 n=n->next;
65         }
66         return n->data;
67 }
68 
69 main()
70 {
71         int seq[]={1,2,3,4,5,6,7,8,9};
72         int size;
73         pLL pll;
74         pll=NULL;
75         size=sizeof(seq)/sizeof(seq[0]);
76         pll=createLL(seq,size);
77 
78         int k=3;
79         printf("The %dth node from the last is:%d\n",k,lastKnode(pll,k));
80 }