19.1.29 [LeetCode 19] Remove Nth Node From End of List

Given a linked list, remove the n-th node from the end of list and return its head.

Example:

Given linked list: 1->2->3->4->5, and n = 2.

After removing the second node from the end, the linked list becomes 1->2->3->5.

Note:

Given n will always be valid.

Follow up:

Could you do this in one pass?

 1 class Solution {
 2 public:
 3     ListNode* removeNthFromEnd(ListNode* head, int n) {
 4         ListNode hh(0);
 5         hh.next = head;
 6         ListNode*hhead = &hh;
 7         ListNode*first = hhead, *second = hhead->next->next;
 8         int count = 0;
 9         while (head) {
10             count++;
11             if (count >= n+1) {
12                 first = first->next;
13                 second = second->next;
14             }
15             if (head->next == NULL) {
16                 first->next = second;
17                 break;
18             }
19             head = head->next;
20         }
21         return hhead->next;
22     }
23 };

View Code

注定失败的战争，也要拼尽全力去打赢它；就算输，也要输得足够漂亮。