反转一个单链表。
示例:
输入: 1->2->3->4->5->NULL
输出: 5->4->3->2->1->NULL
进阶:
你可以迭代或递归地反转链表。你能否用两种方法解决这道题?
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/reverse-linked-list
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package LeetCode;
import java.util.Stack;
public class ReverseList {
public ListNode reverseList(ListNode head) {
ListNode res=new ListNode(0);
Stack<Integer> stack=new Stack<>();
while(head!=null){
stack.push(head.val);
head=head.next;
}
ListNode resheader=new ListNode(0);
resheader.next=res;
while(!stack.isEmpty()){
ListNode ns=new ListNode(stack.pop());
res.next=ns;
res=res.next;
}
return resheader.next.next;
}
public static void main(String[] args) {
ReverseList reverseList=new ReverseList();
ListNode s1=new ListNode(1);
ListNode s2=new ListNode(2);
ListNode s3=new ListNode(3);
ListNode s4=new ListNode(4);
ListNode s5=new ListNode(5);
s1.next=s2;
s2.next=s3;
s3.next=s4;
s4.next=s5;
reverseList.reverseList(s1);
}
}