《剑指Offer》15反转链表

class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}
public class Solution {
    public ListNode ReverseList(ListNode pHead) {  ListNode pHeadNode=null;  ListNode pNode=pHead;  ListNode pNext=null;  ListNode pRev=null;  while(pNode!=null) {  pNext=pNode.next;  if(pNext==null) {  pHeadNode=pNode;  }  pNode.next=pRev;  pRev=pNode;  pNode=pNext;  }  return pHeadNode;
    }
}

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {  public ListNode ReverseList(ListNode head) {  ListNode pHead=null;  ListNode pNode=head;  ListNode pNext=null;  ListNode pRev=null;  while(pNode!=null) {  pNext=pNode.next;  if (pNext==null) {  pHead=pNode;  }  pNode.next=pRev;  pRev=pNode;  pNode=pNext;  }  return pHead;  }
}