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[LeetCode] Remove Nth Node From End of List

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.

增加一个头结点,解决有可能需要删除原head问题,就不需要单独处理了。

/** * 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) {        if(head==NULL || n==0)            return head;        ListNode *h = new ListNode(0);        h->next = head;                ListNode *p1 = h,*p2 = h;        int num = 0;        while(num!=n){            p2 = p2->next;            num++;        }                while(p2->next != NULL){            p1 = p1->next;            p2 = p2->next;        }        ListNode *p = p1->next->next;        p1->next = p;        return h->next;            }

 

[LeetCode] Remove Nth Node From End of List