206Reverse Linked List

Reverse a singly linked list.

总体思路是很简单的，按照将元素插入到链头的思路进行

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode reverseList(ListNode head) {        if(head == null){            return head;        }        ListNode p = head.next;        head.next = null;        ListNode q = null;        while(p != null){            q = p.next;            p.next = head;            head = p;            p = q;        }        return head;    }}