Given a linked list, determine if it has a cycle in it.
Follow up:
Can you solve it without using extra space?
用两个指针，一快一慢，如果有cycle肯定会交汇
/**
* Definition for singly-linked list.
* class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public boolean hasCycle(ListNode head) {
if(head == null) return false;
ListNode slow = head;
ListNode fast = head;
while(fast.next != null && fast.next.next != null){
slow =slow.next;
fast = fast.next.next;
if(slow == fast){
return true;
}
}
return false;
}
}
本站原创文章皆遵循“署名-非商业性使用-相同方式共享 3.0 (CC BY-NC-SA 3.0)”。转载请保留以下标注：
