题解 | 合并两个排序的链表

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param pHead1 ListNode类 
 * @param pHead2 ListNode类 
 * @return ListNode类
 */
struct ListNode* Merge(struct ListNode* pHead1, struct ListNode* pHead2 ) {
    // write code here
    if (!pHead1) return pHead2;
    if (!pHead2) return pHead1;

    struct ListNode* head,*tail;
    if (pHead1->val < pHead2->val)
      {
        head = tail = pHead1;
        pHead1 = pHead1->next;
      }
    else
      {
        head = tail = pHead2;
        pHead2 = pHead2->next;
      }
    while (pHead1 && pHead2)
      {
        if (pHead1->val > pHead2->val)
          {
            tail->next = pHead2;
            pHead2 = pHead2->next;
          }
        else
          {
            tail->next = pHead1;
            pHead1 = pHead1->next;
          }
        tail = tail->next;
      }
      if (pHead1)
        {
          tail->next = pHead1;
        }
      if (pHead2)
        {
          tail->next = pHead2;
        }

    return head;
}

两个链表完成，head负责保存链表的表头，tail负责添加后续的元素