单链表反转

/**
* 节点定义
**/
static class Node {
        Integer data;
        Node next;

        @Override
        public String toString() {
            return this.data.toString();
        }
 }
/**
* 生成节点数据
**/
static Node readyNode() {
        Node linkNode1 = new Node();
        linkNode1.data = 1;
        Node linkNode2 = new Node();
        linkNode2.data = 2;
        Node linkNode3 = new Node();
        linkNode3.data = 3;
        Node linkNode4 = new Node();
        linkNode4.data = 4;
        Node linkNode5 = new Node();
        linkNode5.data = 5;
        Node linkNode6 = new Node();
        linkNode6.data = 6;
        linkNode1.next = linkNode2;
        linkNode2.next = linkNode3;
        linkNode3.next = linkNode4;
        linkNode4.next = linkNode5;
        linkNode5.next = linkNode6;
        return linkNode1;
    }

/**
* 递归方式反转
**/
static Node reverse(Node head) {
        //我们从原链表的头结点开始
        Node cur = head;
        //递归到原链表的尾节点结束。递归到了尾节点的时候就返回当前节点
        if(cur.next == null){
            return cur;
        }else{
            Node reHead = reverse(cur.next);
            cur.next.next = cur;
            cur.next = null;
            return reHead;
        }

    }

/**
* 循环方式反转
**/
static Node reverse2(Node pHead) {
        if (pHead == null) {
            return pHead;
        }
        Node prev = null;
        while (pHead != null) {
            //保存next
            Node temp = pHead.next;
            //反转
            pHead.next = prev;
            //移动prev
            prev = pHead;
            //移动pHead
            pHead = temp;
        }
        return prev;
    }

/**
** 内置法
** LinkedList没有提供反转链表的相关函数，以下是通过foreach实现链表反转
**/
static LinkedList reverse(LinkedList linkedList) {
    LinkedList<Object> newLinkedList = new LinkedList<>();
    for (Object object : linkedList) {
        newLinkedList.add(0, object);
    }
    return newLinkedList;
}