<div id="div15"><h4> 15, 反转链表 <h4></div>   ```javascript /* function ListNode(x){ this.val = x; this.next = null; }*/ function ReverseList(pHead) { // write code here let pPre = null, pNext = null; while (pHead !== null) { pNext = pHead.next; pHead.next = pPre; pPre = pHead; pHead = pNext; } return pPre; } ```