Remove Nth Node From End of List ——解题报告

【题目】

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.

【分析】

两指针法。先让first领先n-1步,然后first和second一起移动,当first到底的时候,second即为倒数第k个节点。题目需要删除,所以我们再额外记录second的前节点。

注意其中特殊情况的考虑。

【代码】

/**
 * 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* first = head;
        ListNode* second = head;
        ListNode* pre = NULL;
        for(int i = 0; i < n - 1; i++) // 中间间隔N-1的距离
            first = first->next;
        while(first->next != NULL)
        {
            pre = second;  // pre是倒数第k个节点的前一个节点,用来删除
            second = second->next;  // second是倒数第k个节点
            first = first->next;
        }

        if(pre == NULL)  // 如果倒数第k个节点就是head,那么pre会保留原来的NULL,这时head直接是倒数第k个节点second的下一个节点
            head = second->next;
        else
            pre->next = second->next;

        return head;
    }
};
时间: 2024-11-08 14:24:37

Remove Nth Node From End of List ——解题报告的相关文章

LeetCode: Remove Nth Node From End of List 解题报告

Remove Nth Node From End of List Total Accepted: 46720 Total Submissions: 168596My Submissions Question Solution 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,

【LeetCode】 19. Remove Nth Node From End of List 解题小结

题目: 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. 首先容易想到的是

leetCode 19.Remove Nth Node From End of List(删除倒数第n个节点) 解题思路和方法

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

LeetCode:Remove Nth Node From End of List

1.题目名称 Remove Nth Node From End of List(移除链表中倒数第n项) 2.题目地址 https://leetcode.com/problems/remove-nth-node-from-end-of-list/ 3.题目内容 英文:Given a linked list, remove the nth node from the end of list and return its head. 中文:给出一个链表,删去链表中的倒数第n项,返回链表首节点 例如:

[leetcode]Remove Nth Node From End of List @ Python

原题地址:http://oj.leetcode.com/problems/remove-nth-node-from-end-of-list/ 题意: 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 n

LeetCode OJ - Remove Nth Node From End of List

题目: 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:Give

Merge Two Sorted Lists &amp; Remove Nth Node From End of List

1.合并两个排好序的list Merge Two Sorted Lists Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 2.删除list倒数第n个元素 Remove Nth Node From End of List Given a linked list,

[Leetcode][Python]19: Remove Nth Node From End of List

# -*- coding: utf8 -*-'''__author__ = '[email protected]' 19: Remove Nth Node From End of Listhttps://oj.leetcode.com/problems/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 ex

63. Swap Nodes in Pairs &amp;&amp; Rotate List &amp;&amp; Remove Nth Node From End of List

Swap Nodes in Pairs Given a linked list, swap every two adjacent nodes and return its head. For example, Given 1->2->3->4, you should return the list as 2->1->4->3. Your algorithm should use only constant space. You may not modify the va