题解 | #两个链表的第一个公共结点#

# 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
        if not pHead1 or not pHead2:return None
        start1=pHead1
        start2=pHead2
        flag=0
        while start1!=start2:
            start1=start1.next
            start2=start2.next
            if not start1: 
                if flag==1:
                    flag=2
                    break
                start1=pHead2
                flag=1
            if not start2: 
                start2=pHead1
        if flag==2: return None
        return start1