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leetcode第19题--Remove Nth Node From End of List

Problem:

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.

果然一次就通过了。先读到尾,知道长度后,再从头开始读到要去掉的前一位,然后把要去掉的next复制给要去掉的前一个的next就可以。

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:ListNode *removeNthFromEnd(ListNode *head, int n){    int len = 1;    ListNode *tmp = head;    while(tmp -> next != NULL)    {        len++;        tmp = tmp -> next;    }    if (len == n)        return head -> next;    ListNode *p = head;    for(int i = 1; i < len - n; i++)    {        p = p -> next;    }    p -> next = p -> next -> next;    return head;}};

 

leetcode第19题--Remove Nth Node From End of List