[Leetcode][python]Remove Nth Node From End of List

class Solution(object):
    def removeNthFromEnd(self, head, n):
        """
        :type head: ListNode
        :type n: int
        :rtype: ListNode
        """
        dummy = ListNode(0)
        dummy.next = head
        p1 = p2 = dummy
        while n: 
            p1=p1.next
            n -= 1
        while p1.next:  # p1ºóÖ¸ÕëÖ¸Ïò¿ÕºóÌø³ö
            p1 = p1.next
            p2 = p2.next
        p2.next = p2.next.next
        return dummy.next