1 /*
2 题目:输入一个单向链表,输出该链表中倒数第 k 个结点。链表的倒数第 0 个结点为链表
3 的尾指针。
4 链表结点定义如下:
5 struct node
6 {
7 int data;
8 struct node *next;
9 };
10 typedef struct node* PtrToNode;
11 typedef PtrToNode Position;
12 typedef Position List;
13 */
14 #include <iostream>
15 #include <assert.h>
16 #include "./List.h"
17 using namespace std;
18 void print_list(List list)
19 {
20 assert(list != NULL);
21 list = First(list);
22 while(list != NULL)
23 {
24 cout<<list->data<<" ";
25 list = list->next;
26 }
27 cout<<endl;
28 }
29 Position get_last_kth(List list, int k)
30 {
31 assert(list != NULL);
32 Position tmp = First(list);
33 while(tmp != NULL && --k >= 0)
34 tmp = tmp->next;
35 if(NULL == tmp)//the length of list <= k
36 return NULL;
37 Position ret = First(list);
38 while(tmp != NULL)
39 {
40 ret = ret->next;
41 tmp = tmp->next;
42 }
43 return ret;
44 }
45 int main(int argc, char const *argv[])
46 {
47 List list = CreateEmptyList();
48 int k;
49 for(int i = 1; i != 20; ++i)
50 PushBack(i, list);
51 print_list(list);
52 while(cin>>k)
53 {
54 Position tmp = get_last_kth(list, k);
55 cout<<"k:"<<k<<" = ";
56 if(tmp == NULL)
57 cout<<"NULL";
58 else
59 cout<<tmp->data;
60 cout<<endl;
61 }
62 return 0;
63 }
