[LeedCode OJ] #206 Reverse Linked List

Source: Internet
Author: User

[LeedCode OJ] #206 Reverse Linked List




Given a linked list, you must obtain its reverse linked list.



It is easy to think that we can change the next pointer of each node to point to the previous node, but this leads to a poor search for the subsequent nodes, so we can open three pointers, record the current node, the previous node, and the next node respectively.



/*** 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) {ListNode * pre = nullptr; ListNode * newhead = nullptr; ListNode * node = head; while (node! = Nullptr) {ListNode * next = node-> next; if (next = nullptr) newhead = node; node-> next = pre; pre = node; node = next ;} return newhead ;}};



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