[LeetCode][Javascript] LinkedList Problems

141. Linked List Cycle

 

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */

/**
 * @param {ListNode} head
 * @return {boolean}
 */
var hasCycle = function(head) {
    let fast= head;
    let ans=false;
    while(fast&&fast.next&&head){
        head=head.next
        fast=fast.next.next
        if(head===fast) {
            ans=true;
            break;
        }
    }
    
   return ans

};