题解 | #链表中环的入口结点#

package main

//双指针法
func EntryNodeOfLoop(pHead *ListNode) *ListNode{
    if pHead == nil || pHead.Next == nil {
        return nil 
    }

    fast , slow := pHead, pHead
    for fast != nil && fast.Next.Next != nil {
        fast = fast.Next.Next
        slow = slow.Next

        if fast == slow {
            tmp := pHead
            for tmp != slow {
                tmp = tmp.Next
                slow = slow.Next
            }
            return tmp
        }
    }
    return nil 
}