题解 | #链表中环的入口结点#
链表中环的入口结点
https://www.nowcoder.com/practice/253d2c59ec3e4bc68da16833f79a38e4
2(x+m)=x+k(m+n)得x=(k-1)m+kn令k=1，可以得出相遇的时候指，针和原点同时出发会在入口点相遇
package main
type ListNode struct {
Val int
Next *ListNode
}
func EntryNodeOfLoop(pHead *ListNode) *ListNode {
if pHead == nil || pHead.Next == nil {
return nil
}
low, fast := pHead, pHead
for fast.Next != nil && fast.Next.Next != nil {
low = low.Next
fast = fast.Next.Next
if low == fast {
for pHead != low {
pHead = pHead.Next
low = low.Next
}
return low
}
}
return nil
}
