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• Reverse a singly linked list.
• • click to show more hints.
• • Hint:
• A linked list can be reversed either iteratively or recursively. Could you implement both?
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ListNode* reverseList(ListNode* head) {        if (head==NULL||head->next==NULL)            return head;        ListNode *pre=head;ListNode *cur=pre->next;        pre->next=NULL;        while (cur) {            ListNode *nxt=cur->next;            cur->next=pre;            pre=cur;            cur=nxt;        }        return pre;    }

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* * Reverse a linked list from position m to n. Do it in-place and in one-pass. * * For example: * Given 1->2->3->4->5->NULL, m = 2 and n = 4, * * return 1->4->3->2->5->NULL. * * Note: * Given m, n satisfy the following condition: * 1 ≤ m ≤ n ≤ length of list. * * ************************************************************************/

ListNode* reverseBetween(ListNode* head, int m, int n) {        if (m==n) return head;        ListNode preHead(0),*pre=&preHead;        preHead.next=head;        for (int i=0;i
   
    next;        ListNode *cur=pre->next;        for (int i=0;i
    
     next;            cur->next=nxt->next;            nxt->next=pre->next;            pre->next=nxt;        }        return preHead.next;    }