[LeetCode]Remove Nth Node From End of List
2015-02-03 12:25
411 查看
Q:Given a linked list, remove the nth node
from the end of list and return its head.
For example,
Note:
Given n will always be valid.
Try to do this in one pass.//在一次遍历中解决
这个问题是删除链表倒数第n个结点。如果没有条件限制,可以先一次遍历该链表求出链表的长度,然后再遍历定位到第len-n个结点,删除;但是这里要求只能遍历一次,所以使用两个指针pre和post,post-pre=n-1。二者同时后移,当post到达最后一个结点时,pre所指的结点就是要删除的结点。
思路很简单,但是容易出错,要考虑多个边界问题:
1. 链表为空,直接返回
2. 链表的长度小于n
为了方便,增加一个头结点,指向head。一开始没有使用头结点,在len <= n 的情况下出错,因为删除无头结点的链表的头结点和中间结点,处理方式是不同的;为了统一,加上头结点。
下面贴上代码:
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.//在一次遍历中解决
这个问题是删除链表倒数第n个结点。如果没有条件限制,可以先一次遍历该链表求出链表的长度,然后再遍历定位到第len-n个结点,删除;但是这里要求只能遍历一次,所以使用两个指针pre和post,post-pre=n-1。二者同时后移,当post到达最后一个结点时,pre所指的结点就是要删除的结点。
思路很简单,但是容易出错,要考虑多个边界问题:
1. 链表为空,直接返回
2. 链表的长度小于n
为了方便,增加一个头结点,指向head。一开始没有使用头结点,在len <= n 的情况下出错,因为删除无头结点的链表的头结点和中间结点,处理方式是不同的;为了统一,加上头结点。
下面贴上代码:
class Solution { public: ListNode *removeNthFromEnd(ListNode *head, int n) { ListNode* temp = new ListNode(0); temp->next = head; if (head != NULL){ ListNode* pre = head; ListNode* post = head; ListNode* prepre = temp; for (int i = 0; i < n-1; i++){ post = post->next; if (post == NULL) break; } if(post != NULL){ while (post->next != NULL){ post = post->next; pre = pre->next; prepre = prepre->next; } ListNode* node = prepre->next; prepre->next = node->next; delete node; } } return temp->next; } };
相关文章推荐
- leetcode -- Remove Nth Node From End of List
- [Leetcode] Remove Nth Node From End of List
- LeetCode 19: Remove Nth Node From End of List
- LeetCode: Remove Nth Node From End of List
- LeetCode - Remove Nth Node From End of List
- [LeetCode] Remove Nth Node From End of List
- [LeetCode] Remove Nth Node From End of List 解题报告
- leetcode 40: Remove Nth Node From End of List
- [LeetCode] Remove Nth Node From End of List
- [LeetCode] Remove Nth Node From End of List
- LeetCode 笔记系列四 Remove Nth Node From End of List
- LeetCode-Remove Nth Node From End of List
- leetcode 40: Remove Nth Node From End of List
- [LeetCode]Remove Nth Node From End of List
- [leetcode]Remove Nth Node From End of List
- LeetCode: Remove Nth Node From End of List
- [leetcode刷题系列]Remove Nth Node From End of List
- leetcode--Remove Nth Node From End of List
- LeetCode-Remove Nth Node From End of List
- LeetCode: Remove Nth Node From End of List