反转单链表。
class Solution { public: ListNode* reverseList(ListNode* head) { if (NULL == head) { return head; } ListNode * before = NULL; ListNode * now = head; ListNode * next = now->next;</p> <pre><code> while (NULL != next) { ListNode * beforeTmp = now; ListNode * nowTmp = next; ListNode * nextTmp = next-&gt;next; now-&gt;next = before; next-&gt;next = now; before = beforeTmp; now = nowTmp; next = nextTmp; } head = now; return head; } </code></pre> <p>};