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/**
* 反转单链表
*/
/** * 定义链表
*
* @author 16026
*
*/
class Node {
int val;
Node next;
public Node(int val) {
this.val = val;
}
}
public class ReverseList {
/**
* 反转链表
*
* @param head
* @return
*/
public static Node reverseList(Node head) {
if (head == null || head.next == null) {
return head;
}
Node reHead = null;// 定义新链表头结点
while (head != null) {
Node cur = head.next;// 记录下一个节点
head.next = reHead;// 将rehead节点连接到head节点上
reHead = head;// 让rehead指向head
head = cur;// 将head指向下一个节点
}
return reHead;
}
/**
* 递归反转链表
*
* @param head
* @return
*/
public static Node reverseList2(Node head) {
if (head == null || head.next == null)
return head;
Node rehead = reverseList2(head.next);
head.next.next = head;// 将头节点置于末端
head.next = null;// 防止链表循环
return rehead;
}
/**
* 打印链表
*
* @param head
*/
public static void printList(Node head) {
if (head == null)
return;
while (head != null) {
System.out.print(head.val + " ");
head = head.next;
}
}
/**
* 测试
*
* @param args
*/
public static void main(String[] args) {
Node n1 = new Node(1);
Node n2 = new Node(2);
Node n3 = new Node(3);
Node n4 = new Node(4);
Node n5 = new Node(5);
n1.next = n2;
n2.next = n3;
n3.next = n4;
n4.next = n5;
// Node rehead = reverseList(n1);
Node rehead = reverseList2(n1);
printList(rehead);
}
}
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