19. Remove Nth Node From End of List

Given a linked list, remove thenthnode from the end of list and return its head.

For example,

Givenlinkedlist:1->2->3->4->5,andn=2.Afterremovingthesecondnodefromtheend,thelinkedlistbecomes1->2->3->5.

Note:
Givennwill always be valid.
Try to do this in one pass.

题目大意：

找到链表中倒数第N个元素，删除这个元素。

代码如下：

/***Definitionforsingly-linkedlist.*structListNode{*intval;*ListNode*next;*ListNode(intx):val(x),next(NULL){}*};*/classSolution{public:intlengthOfList(ListNode*head){inti=0;while(head!=NULL){i++;head=head->next;}returni;}ListNode*removeNthFromEnd(ListNode*head,intn){if(head==NULL)returnNULL;ListNode*p=head;intpre=lengthOfList(head)-n;if(pre==0)returnhead->next;cout<<pre<<""<<lengthOfList(head)<<endl;while(--pre)p=p->next;p->next=p->next->next;returnhead;}};

2016-08-12 14:02:00