反转链表

输入一个链表，反转链表后，输出链表的所有元素。

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

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode ReverseList(ListNode head) {
        ListNode pReversedHead = null;
        ListNode pNode = head;
        ListNode pPrev = null;

        while(pNode != null)
        {
            ListNode pNext = pNode.next;
            if(pNext  == null)
                pReversedHead = pNode;

            pNode.next = pPrev;

            pPrev = pNode;
            pNode = pNext;
        }
        return pReversedHead;
    }
}