LEETCODE 2022 Added solution for sort-list

src/leetcode/linked-list.md

@@ -1 +1,41 @@
-# Linked List
+# Linked List
++ [Sort List](#sort-list)
+## Sort List
+https://leetcode.com/problems/sort-list/
+```java
+class Solution {
+    private ListNode mergeSort(ListNode l1, ListNode l2) {
+        ListNode result = new ListNode();
+        ListNode StartPointer = result;
+        while (l1 != null && l2 != null) {
+            if (l1.val <= l2.val) {
+                StartPointer.next = l1;
+                l1 = l1.next;
+            } else {
+                StartPointer.next = l2;
+                l2 = l2.next;
+            }
+            StartPointer = StartPointer.next;
+        }
+        if (l1 != null) StartPointer.next = l1;
+        else StartPointer.next = l2;
+        return result.next;
+    }
+    public ListNode sortList(ListNode headList) {
+        if (headList == null || headList.next == null) return headList;
+        ListNode fast = headList;
+        ListNode slow = headList;
+        ListNode middlePointer = null;
+        while (fast != null && fast.next != null) {
+            middlePointer = slow;
+            fast = fast.next.next;
+            slow = slow.next;
+        }
+        middlePointer.next = null;
+        ListNode left = sortList(headList);
+        ListNode right = sortList(slow);
+        return mergeSort(left, right);
+    }
+}
+
+```