Time: 130 ms (74.55%), Space: 46.1 MB (45.81%) - LeetHub

Author: froghramar

148-sort-list/148-sort-list.cs

@@ -0,0 +1,68 @@
+public class Solution {
+    public ListNode SortList(ListNode head) {
+        if (head?.next == null)
+        {
+            return head;
+        }
+
+        ListNode mid = head, cur = head.next;
+        while (cur != null)
+        {
+            cur = cur.next;
+
+            if (cur != null)
+            {
+                cur = cur.next;
+                mid = mid.next;
+            }
+        }
+
+        var first = head;
+        var second = mid.next;
+        mid.next = null;
+
+        first = SortList(first);
+        second = SortList(second);
+
+        ListNode result = null, resultTail = null;
+
+        while (first != null && second != null)
+        {
+            if (first.val < second.val)
+            {
+                AddToResult(first);
+                first = first.next;
+            }
+            else
+            {
+                AddToResult(second);
+                second = second.next;
+            }
+        }
+
+        if (first != null)
+        {
+            AddToResult(first);
+        }
+
+        if (second != null)
+        {
+            AddToResult(second);
+        }
+
+        void AddToResult(ListNode node)
+        {
+            if (resultTail == null)
+            {
+                result = resultTail = node;
+            }
+            else
+            {
+                resultTail.next = node;
+                resultTail = node;
+            }
+        }
+        
+        return result;
+    }
+}