/*
* function ListNode(x){
* this.val = x;
* this.next = null;
* }
*/
/**
*
* @param head ListNode类
* @return bool布尔型
*/
function hasCycle( head ) {
let slow = head;
let fast = head;
while(slow && fast) {
slow = slow.next;
if (fast.next) {
fast = fast.next.next;
} else {
return false;
}
if(slow == fast) {
return true;
}
}
return false;
}
module.exports = {
hasCycle : hasCycle
};