题解 | #反转链表#

/**
 * struct ListNode {
 *    int val;
 *    struct ListNode *next;
 * };
 */

/**
 * 
 * @param pHead ListNode类 
 * @return ListNode类
 */
struct ListNode* ReverseList(struct ListNode* pHead ) {
    // write code here
    struct ListNode *p=pHead;
    struct ListNode *q,*r;
    if(p!=NULL){
        r=p->next;
        p->next=NULL;
        while(r!=NULL){
            q=r->next;
            r->next=p;
            p=r;
            r=q;
        }
    }
    return p;
}