文章目录
一、题目
Given the head of a linked list, remove the nth node from the end of the list and return its head.
Example 1:
Input: head = 1,2,3,4,5, n = 2
Output: 1,2,3,5
Example 2:
Input: head = 1, n = 1
Output: \[\]
Example 3:
Input: head = 1,2, n = 1
Output: 1
Constraints:
The number of nodes in the list is sz.
1 <= sz <= 30
0 <= Node.val <= 100
1 <= n <= sz
Follow up: Could you do this in one pass?
二、题解
cpp
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode() : val(0), next(nullptr) {}
* ListNode(int x) : val(x), next(nullptr) {}
* ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
ListNode* removeNthFromEnd(ListNode* head, int n) {
ListNode* dummyHead = new ListNode(0);
dummyHead->next = head;
ListNode* fast = dummyHead;
ListNode* slow = dummyHead;
n++;
while(n-- && fast != nullptr){
fast = fast->next;
}
while(fast != nullptr){
fast = fast->next;
slow = slow->next;
}
slow->next = slow->next->next;
return dummyHead->next;
}
};