206 Reverse Linked List

Given the head of a singly linked list, reverse the list, and return the reversed list.

头插法

class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode h = new ListNode();
        ListNode t;
        while(head != null){
            t=head.next;
            head.next=h.next;
            h.next=head;
            head=t;
        }
        return h.next;
    }
}