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 ):
        if pHead1 is None or pHead2 is None: #有一链为空则共享链为空，返回None
            return None 
        inner = pHead2 #内链首部
        outer = pHead1 #外链首部
        while outer:#遍历外链
            while inner: #遍历内链
                if inner == outer: #内外连节点相等，即找了共享链表
                    return inner
                inner = inner.next
            inner = pHead2
            outer = outer.next
        else: #没有找到同用部分就返回None
            return None
        return False