标签：style blog color io strong for div sp log
Given a linked list, remove the nth node from the end of list and return its head.
For 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.
Try to do this in one pass.
1 /** 2 * Definition for singly-linked list. 3 * struct ListNode { 4 * int val; 5 * ListNode *next; 6 * ListNode(int x) : val(x), next(NULL) {} 7 * }; 8 */ 9 class Solution { 10 public: 11 ListNode *removeNthFromEnd(ListNode *head, int n) { 12 if( !head || n < 1 ) return head; //若head为空，或n不合法 13 ListNode node(0); //设置头结点，好删除 14 node.next = head; 15 ListNode* pre = &node; //slow的前驱节点 16 ListNode* fast = head; 17 while( n && fast ) { //令fast先指向第n个节点 18 fast = fast->next; 19 --n; 20 } 21 if( n && !fast ) return head; //若链表长度没有n大 22 ListNode* slow = head; 23 while( fast ) { //fast和slow同时后移，slow为空时结束 24 fast = fast->next; 25 pre = slow; 26 slow = slow->next; 27 } 28 pre->next = slow->next; //删除第n个节点 29 delete slow; 30 return node.next; 31 } 32 };
设立前后两指针，假设为前指针为fast，后指针为slow，先让fast指针指向head，向后走n步，指向第n个节点，然后slow指针指向head，让fast指针和slow指针同时后移，知道slow为空，那么fast指针指向的就是倒数第n个节点
Remove Nth Node From End of List
标签：style blog color io strong for div sp log
原文地址：http://www.cnblogs.com/bugfly/p/3974244.html
