题解 | #判断链表中是否有环#JAVA/C++/Go/Python
判断链表中是否有环
http://www.nowcoder.com/practice/650474f313294468a4ded3ce0f7898b9
JAVA
public class Solution {
public boolean hasCycle(ListNode head) {
if(head == null) return false;
ListNode fast = head;
ListNode slow = head;
while(fast!=null&&fast.next!=null){
slow = slow.next;
fast = fast.next.next;
if(slow == fast) return true;
}
return false;
}
}
C++
class Solution {
public:
bool hasCycle(ListNode *head) {
if(head==NULL) return false;
ListNode* fast=head;
ListNode* slow=head;
while(fast!=NULL&&fast->next!=NULL)
{
fast=fast->next->next;
slow=slow->next;
if(fast==slow)
return true;
}
return false;
}
};
Go
func hasCycle( head *ListNode ) bool {
// write code here
fast := head
slow := head
for fast != nil && fast.Next != nil{
slow = slow.Next
fast = fast.Next.Next
if slow == fast{
return true
}
}
return false
}
Python
class Solution: def hasCycle(self , head ): # write code here slow = head fast = head while(fast is not None and fast.next is not None): slow = slow.next fast = fast.next.next if slow == fast: return True return False
