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
        tmp1=pHead1
        tmp2=pHead2
        while tmp1 and tmp2:
            if tmp1==tmp2:
                return tmp2
            tmp1=tmp1.next
            tmp2=tmp2.next
        if tmp1:
            k=0
            while tmp1:
                tmp1=tmp1.next
                k+=1
            tmp1=pHead1
            tmp2=pHead2
            for i in range(k):
                tmp1=tmp1.next
            while tmp1!=tmp2:
                if tmp1==tmp2:
                    return tmp2
                tmp1=tmp1.next
                tmp2=tmp2.next
            return tmp1
        if tmp2:
            k=0
            while tmp2:
                tmp2=tmp2.next
                k+=1
            tmp2=pHead2
            tmp1=pHead1
            for i in range(k):
                tmp2=tmp2.next
            while tmp2!=tmp1:
                tmp2=tmp2.next
                tmp1=tmp1.next
            return tmp2