✨ [141] Floyd's algorithms

Author: enkr1

141/my_solution.js

@@ -0,0 +1,24 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+const hasCycle = (head) => { // Bad memory O(n)
+  let hashMap = new Map();
+
+  while (null !== head) {
+    if (undefined !== hashMap.get(head)) return true;
+
+    hashMap.set(head, 0);
+    head = head.next;
+  }
+
+  return false;
+}

141/solution.js

@@ -0,0 +1,23 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+const hasCycle = (head) => { // O(n), O(1)
+  let slow = head, fast = head;
+
+  while (null !== fast && null !== fast.next) {
+    slow = slow.next;
+    fast = fast.next.next;
+    if (slow == fast) return true;
+  }
+
+  return false;
+}