剑指offer之十四---反转链表

题目描述

public static ListNode ReverseList(ListNode head){
if(head == null)
return null;
else{
Stack<ListNode> stack = new Stack<ListNode>();
ListNode p = head;
while(p != null){
stack.push(p);
p = p.next;
}
ListNode q = stack.pop();
System.out.println(q.val);
ListNode t = q;//需要返回链表头结点，所以重新声明一个指针
while(!stack.empty()){
q.next = stack.pop();
q = q.next;
System.out.println(q.val);
}
q.next = null;
return t;
}
}