LeetCode-206.ReverseLinked List

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

Follow up:A linked list can be reversed either iteratively or recursively. Could you implement both?

public ListNode reverseList(ListNode head) {//链表 迭代 my
        ListNode nhead = null;
        ListNode curr = head;
        while(null!=curr){
            head=head.next;
            curr.next=nhead;
            nhead=curr;
            curr=head;
        }
        return nhead;
    }　　

　　

递归

public ListNode reverseList(ListNode head) {
    if (head == null || head.next == null) return head;
    ListNode p = reverseList(head.next);
    head.next.next = head;
    head.next = null;
    return p;
}

　

进阶题

两两交换链表中的结点 LeetCode24 https://www.cnblogs.com/zhacai/p/10559271.html　

每 k 个节点一组翻转链表 LeetCode25  https://www.cnblogs.com/zhacai/p/10563446.html