《Cracking the Coding Interview》——第2章：链表——题目3

2014-03-18 02:25

题目：给定一个单链表中间的节点，删掉那个节点。

解法：把后面节点的数据域拷到当前节点来，然后删除后面那个节点。当前节点不是尾巴，所以后面不为空。

代码：

 1 // 2.2 Remove a node from middle of a linked list

 2 #include <cstdio>

 3 using namespace std;

 4 

 5 struct ListNode {

 6     int val;

 7     struct ListNode *next;

 8     ListNode(int x): val(x), next(nullptr) {};

 9 };

10 

11 class Solution {

12 public:

13     void deleteThatNode(ListNode *ptr) {

14         if (ptr != nullptr && ptr->next != nullptr) {

15             struct ListNode *tmp = ptr->next;

16             ptr->val = tmp->val;

17             ptr->next = tmp->next;

18             delete tmp;

19         }

20     }

21 };

22 

23 int main()

24 {

25     int i;

26     int n, k;

27     int val;

28     struct ListNode *head, *ptr;

29     Solution sol;

30     

31     while (scanf("%d", &n) == 1 && n > 0) {

32         // create a linked list

33         ptr = head = nullptr;

34         for (i = 0; i < n; ++i) {

35             scanf("%d", &val);

36             if (head == nullptr) {

37                 head = ptr = new ListNode(val);

38             } else {

39                 ptr->next = new ListNode(val);

40                 ptr = ptr->next;

41             }

42         }

43         

44         // remove a node from middle of the list

45         scanf("%d", &k);

46         k = k < 1 ? 1 : k;

47         k = k > n ? n : k;

48         ptr = head;

49         for (i = 1; i < k; ++i) {

50             ptr = ptr->next;

51         }

52         sol.deleteThatNode(ptr);

53         

54         // print the list

55         printf("%d", head->val);

56         ptr = head->next;

57         while (ptr != nullptr) {

58             printf("->%d", ptr->val);

59             ptr = ptr->next;

60         }

61         printf("\n");

62         

63         // delete the list

64         while (head != nullptr) {

65             ptr = head->next;

66             delete head;

67             head = ptr;

68         }

69     }

70     

71     return 0;

72 }