148. Sort List (java)

Author: bluesword12350

solution/0148.Sort List/Solution.java

@@ -0,0 +1,34 @@
+class Solution {
+    public ListNode sortList(ListNode head) {
+        if(head == null || head.next == null) return head;
+        int len = 0;
+        ListNode cur = head;
+        while(cur != null){
+            len++;
+            cur = cur.next;
+        }
+        ListNode left = head,right = head;
+        for(int i = 0; i < len/2 - 1; i++) right = right.next;
+        ListNode leftTail = right;
+        right = right.next;
+        leftTail.next = null;
+        left = sortList(left);
+        right = sortList(right);
+        ListNode dummy = new ListNode(0);
+        cur = dummy;
+        while(left != null && right != null){
+            if(left.val < right.val){
+                cur.next = left;
+                left = left.next;
+            }else{
+                cur.next = right;
+                right = right.next;
+            }
+            cur = cur.next;
+        }
+        if(left != null) cur.next = left;
+        else if(right != null) cur.next = right;
+        else cur.next = null;
+        return dummy.next;
+    }
+}