两个链表的第一个公共结点

题目描述
输入两个链表，找出它们的第一个公共结点。

python solution:

# -*- coding:utf-8 -*-
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution:
    def FindFirstCommonNode(self, pHead1, pHead2):
        if pHead2 is None or pHead1 is None:
            return None
        work1,work2 = pHead1,pHead2
        l1,l2 = 1,1
        while work1.next:
            work1 = work1.next
            l1 += 1
        while work2.next:
            work2 = work2.next
            l2 += 1
        path = abs(l1-l2)
        if l1<l2:
            pHead1,pHead2 = pHead2,pHead1
        for i in range(path):
            pHead1 = pHead1.next
        while pHead1!=pHead2:
            pHead1 = pHead1.next
            pHead2 = pHead2.next
        return pHead2