题解 | #两个链表的第一个公共结点# if n1 else pHead2 (1遍历完，遍历2)

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

#
# 
# @param pHead1 ListNode类 
# @param pHead2 ListNode类 
# @return ListNode类
#
class Solution:
    def FindFirstCommonNode(self , pHead1 , pHead2 ):
        # write code here
        n1=pHead1
        n2=pHead2
        while n1!=n2:
            n1=n1.next if n1 else pHead2 # n1达到pHead1终点时，从phead2开始
            n2=n2.next if n2 else pHead1 # n2达到pHead2终点时，从phead1开始
        
        return n1

n1=n1.next if n1 else pHead2 # n1达到pHead1终点时，从phead2开始

n2=n2.next if n2 else pHead1 # n2达到pHead2终点时，从phead1开始