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 *back;
    struct ListNode *p;
    struct ListNode *forward;

    // 检测链表节点数要>1
    if(pHead == NULL || pHead->next == NULL)
    {
        return pHead;
    }

    // 初始化指针值
    back = pHead;
    p = pHead;
    forward = pHead->next;

    while(forward != NULL)
    {
        back = p;
        p = forward;
        forward = forward->next;

        p->next = back;
    }

    pHead->next = NULL;

    return p;

}