Leetcode: Linked List Cycle II @Python

Very interesting problem. Do the math and figure out where the fast and slow pointer met in the previous version of the problem will lead to the solution.

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

class Solution:
    # @param head, a ListNode
    # @return a list node
    def detectCycle(self, head):
        if not head: return None
        slow=fast=head
        while fast and fast.next:
            slow=slow.next
            fast=fast.next.next
            if fast==slow:
                new_point=head
                while new_point!=slow:
                    new_point=new_point.next
                    slow=slow.next
                return new_point
        return None