题解 | #合并两个排序的链表#

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
        
class Solution:
    # 返回合并后列表
    def Merge(self, pHead1, pHead2):
        # write code here
        if not pHead1:
            return pHead2
        if not pHead2:
            return pHead1
        
        result = ListNode(-1)
        cur = result
        while pHead1 and pHead2:
            # 元素对比
            if pHead1.val <= pHead2.val:
                cur.next = pHead1
                pHead1 = pHead1.next
            else:
                cur.next = pHead2
                pHead2 = pHead2.next
            # 指针右移动一位
            cur = cur.next
        # 拼接未对比的链表
        cur.next = pHead1 if pHead1 else pHead2
        return result.next