LeetCode题解之Remove Nth Node From End of List

 1 ListNode* removeNthFromEnd(ListNode* head, int n) {
 2         if (head == NULL)
 3             return head;
 4         int len = 0;
 5         ListNode *p = head;
 6         while (p != NULL) {
 7             len++;
 8             p = p->next;
 9         }
10         
11         int step = len - n;
12         if (step == 0)
13             return head->next;
14         p = head;
15         while (--step) {
16             p = p->next;
17         }
18         
19         ListNode *tmp = p->next->next;
20         p->next = tmp;
21         
22         
23         return head;
24         
25         
26     }