两个链表的第一个公共节点

微信图片_20191222175705.jpg

class Solution:
    def FindFirstCommonNode(self, pHead1, pHead2):
        # write code here
        if pHead1 is None or pHead2 is None:
            return None
        tmp1 = pHead1
        tmp2 = pHead2
        
        len1 = 0
        len2 = 0
        while tmp1:
            len1 += 1
            tmp1 = tmp1.next
        while tmp2:
            len2 += 1
            tmp2 = tmp2.next
        if len1 > len2:
            k = len1 - len2
            for i in range(k):
                pHead1 = pHead1.next
            while pHead1 != pHead2:
                pHead1 = pHead1.next
                pHead2 = pHead2.next
            return pHead1
        else:
            k = len2 - len1
            for i in range(k):
                pHead2 = pHead2.next
            while pHead1 != pHead2:
                pHead1 = pHead1.next
                pHead2 = pHead2.next
            return pHead1