LeetCode-160. 相交链表（Python）

题目链接

题解：

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def getIntersectionNode(self, headA: ListNode, headB: ListNode) -> Optional[ListNode]:
        la=self.length(headA)#引用类内的方法
        lb=self.length(headB)
        p=headA
        q=headB
        if la>lb:
            for i in range(la-lb):
                p=p.next
        else:
            for i in range(lb-la):
                q=q.next
        while  q!=p and q!=None:#注意python中的空值为None，不为null
            q=q.next
            p=p.next
        if q==p:
            return q
        else:
            return null
    def length(self,head):#因为这个方法在类内，所以加self
        p=head
        num=0
        while p!=None:
            num=num+1
            p=p.next
        return num