Last week I learned data structure about Linked List , in which include an algorithm for reversing a linked list . And in this chapter I will introduce this algorithm.

First considering a simple example . You is given a linked list of integers , and the question asks you to invert this linked list.

For example:

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1->2->3->4->5->NULL

5->4->3->2->1->NULL

For iterating through this linked list and inverting it , you can declare three pointers (prev , curr, next), which represent the previous , current , next pointers. And in this way can you search this linked list and invert it iteratively.

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 ListNode* reverseList(ListNode* head) {

​    ListNode* prev=NULL;

​    ListNode* curr=head;

​    while(curr!=NULL)

​    {

​      ListNode* next=curr->next;

​      curr->next=prev;

​      prev=curr;

​      curr=next;

​    }

​    return prev;