题解 | #合并两个排序的链表#

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
            val(x), next(NULL) {
    }
};*/
class Solution {
public:
  ListNode *Merge(ListNode *pHead1, ListNode *pHead2) {
    if (pHead1 == nullptr)
      return pHead2;
    if (pHead2 == nullptr)
      return pHead1;

    ListNode *head = new ListNode(-1);
    ListNode *cur = head;
    while (pHead1 != nullptr && pHead2 != nullptr) {
      if (pHead1->val <= pHead2->val) {
        cur->next = pHead1;
        pHead1 = pHead1->next;
      } else if (pHead1->val > pHead2->val) {
        cur->next = pHead2;
        pHead2 = pHead2->next;
      }
      cur = cur->next;
    }

    if (pHead1 != nullptr)
      cur->next = pHead1;
    if (pHead2 != nullptr)
      cur->next = pHead2;
    return head->next;
  }
};