题解 | #合并两个排序的链表#

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

/**
 * 
 * @param pHead1 ListNode类 
 * @param pHead2 ListNode类 
 * @return ListNode类
 */
struct ListNode* Merge(struct ListNode* pHead1, struct ListNode* pHead2) {
    if(pHead1 == NULL) return pHead2;
    if(pHead2 == NULL) return pHead1;
    struct ListNode* RL = (struct ListNode*)malloc(sizeof(struct ListNode));
    struct ListNode* RLr = NULL;
    RL->next = RLr;
    struct ListNode* q1 = pHead1;
    struct ListNode* q2 = pHead2;
    
    while(q1 && q2) {
        if(q1->val <= q2->val) {
            if(RLr == NULL) {
                RL->next = q1;
                RLr = q1;
            } else {
                RLr->next = q1;
                RLr = q1;
            }
            q1 = q1->next;
        } else {
            if(RLr == NULL) {
                RL->next = q2;
                RLr = q2;
            } else {
                RLr->next = q2;
                RLr = q2;
            }
            q2 = q2->next;
        }
    }

    if(q1 == NULL)
        RLr->next = q2;
    if(q2 == NULL)
        RLr->next = q1;

    return RL->next;
}

c语言很不容易啊，最后死在空指针发生段错误，一定注意判空条件放在最开始，规范书写