[数据结构与算法]golang力扣leetcode 141.环形链表

141.环形链表

141.环形链表

题解

大水题，两种实现方式
思路：快慢指针，快慢指针相同则有环，证明：如果有环每走一步快慢指针距离会减 1

代码

package main

type ListNode struct {
	Val  int
	Next *ListNode
}

func hasCycle1(head *ListNode) bool {
	mp := make(map[*ListNode]bool)
	for head != nil {
		if _, ok := mp[head]; ok {
			return true
		} else {
			mp[head] = true
		}
		head = head.Next
	}
	return false
}
func hasCycle2(head *ListNode) bool {
	if head == nil {
		return false
	}
	fast, slow := head.Next, head
	for fast != nil && fast.Next != nil {
		if fast == slow {
			return true
		}
		fast = fast.Next.Next
		slow = slow.Next
	}
	return false
}
func main() {

}