11package easy
22
3+ import HashTableTopic
4+ import LinkedListTopic
5+ import TwoPointersTopic
36import utils.ListNode
47
58/* *
@@ -12,20 +15,21 @@ import utils.ListNode
1215 * Return true if there is a cycle in the linked list. Otherwise, return false.
1316 */
1417
15- class Easy141 {
18+ class Easy141 : HashTableTopic , LinkedListTopic , TwoPointersTopic {
1619
1720 fun hasCycle (head : ListNode ? ): Boolean {
18- if (head == null ) return false
19- if (head.next == null || head.next!! .next == null ) return false
21+ head ? : return false
22+ head.next ? : return false
23+ head.next?.next ? : return false
2024 if (head == = head.next) return true
2125 var t1 = head
22- var t2 = head.next!! .next
26+ var t2 = head.next? .next
2327 while (true ) {
2428 when {
2529 t1 == = t2 -> return true
26- t2!! .next != null && t2.next!! .next != null -> {
27- t1 = t1!! .next
28- t2 = t2.next!! .next
30+ t2? .next != null && t2.next!! .next != null -> {
31+ t1 = t1? .next
32+ t2 = t2.next? .next
2933 }
3034 else -> return false
3135 }
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