【LeetCode】206. Reverse Linked List

LeetCode-206

Links:https://leetcode.com/problems/reverse-linked-list/

Reverse a singly linked list.

思路：

A->B->C->D

3个指针分别指向ABC，令A->NULL

然后做循环：

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        if(head==NULL || head->next == NULL)return head;
        
        ListNode* temp = head->next;
        ListNode* temp2 = temp->next;
        head->next = NULL;
        while(1)
        {
            temp->next = head;
            head = temp;
            temp = temp2;
            if(temp!=NULL)temp2 = temp->next;
            else return head;
        }
    }
};

/**

* Definition for singly-linked list.

* struct ListNode {

* int val;

* ListNode *next;

* ListNode(int x) : val(x), next(NULL) {}

* };

class Solution {

public:

ListNode* reverseList(ListNode* head) {

if(head==NULL || head->next == NULL)return head;

ListNode* temp = head->next;

ListNode* temp2 = temp->next;

head->next = NULL;

while(1)

{

temp->next = head;

head = temp;

temp = temp2;

if(temp!=NULL)temp2 = temp->next;

else return head;

}

};

【LeetCode】206. Reverse Linked List

Tagged on: LeetCode