Merge pull request #1139 from ChrisKheng/scala

Add scala solution for 141-Linked-List-Cycle and 206-Reverse-Linked-List

Author: Ahmad-A0

Diff for: README.md

@@ -58,14 +58,14 @@ If you would like to have collaborator permissions on the repo to merge your own
 <sub>[153 - Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[981 - Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store/)</sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[4 - Find Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays/)</sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
-<sub>[206 - Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
+<sub>[206 - Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[21 - Merge Two Linked Lists](https://leetcode.com/problems/merge-two-sorted-lists/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[143 - Reorder List](https://leetcode.com/problems/reorder-list/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[19 - Remove Nth Node from End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[138 - Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer/)</sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[2 - Add Two Numbers](https://leetcode.com/problems/add-two-numbers/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
-<sub>[141 - Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
-<sub>[287 - Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub>
+<sub>[141 - Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
+<sub>[287 - Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number/)</sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[146 - LRU Cache](https://leetcode.com/problems/lru-cache/)</sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub>
 <sub>[23 - Merge K Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/)</sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>
 <sub>[25 - Reverse Nodes in K-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/)</sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>✔️</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>❌</div></sub> | <sub><div align='center'>✔️</div></sub>

Diff for: scala/141-Linked-List-Cycle.scala

@@ -0,0 +1,24 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode(var _x: Int = 0) {
+ *   var next: ListNode = null
+ *   var x: Int = _x
+ * }
+ */
+
+object Solution {
+    def hasCycle(head: ListNode): Boolean = {
+        var (slowPtr, fastPtr) = (head, head)
+        
+        while (fastPtr != null && fastPtr.next != null) {
+            slowPtr = slowPtr.next
+            fastPtr = fastPtr.next.next
+            
+            if (slowPtr eq fastPtr) {
+                return true
+            }
+        }
+        
+        return false
+    }
+}

Diff for: scala/206-Reverse-Linked-List.scala

@@ -0,0 +1,20 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode(_x: Int = 0, _next: ListNode = null) {
+ *   var next: ListNode = _next
+ *   var x: Int = _x
+ * }
+ */
+object Solution {
+    def reverseList(head: ListNode): ListNode = {
+        if (head == null || head.next == null) {
+            return head
+        }
+        
+        val reversedListHead = reverseList(head.next)
+        head.next.next = head
+        head.next = null
+        
+        return reversedListHead
+    }
+}