Update 0148-排序链表.py

Author: zaie

0148.排序链表/0148-排序链表.py

@@ -10,9 +10,9 @@ def sortList(self, head):
         :type head: ListNode
         :rtype: ListNode
         """
-        #1. 一分为二
-        #2. 各自排序
-        #3. 合二为一
+        #1. 一分为二
+        #2. 各自排序
+        #3. 合二为一
 
         if not head or not head.next:
             return head
@@ -48,4 +48,53 @@ def merge(self, l1, l2):
             tmp = ListNode(l2.val)
             tmp.next = self.merge(l1, l2.next)
 
-        return tmp
+        return tmp
+    
+# 应该和上面的思路相同
+        #1. 一分为二
+        #2. 各自排序
+        #3. 合二为一
+class Solution:
+    def sortList(self, head: ListNode) -> ListNode:
+        if not head or not head.next: 
+            return head
+        slow = head
+        fast = head
+        # 用快慢指针分成两部分
+        while fast.next and fast.next.next:
+            slow = slow.next
+            fast = fast.next.next
+        # 找到左右部分, 把左部分最后置空
+        mid = slow.next
+        slow.next = None
+        # 递归下去
+        left = self.sortList(head)
+        right = self.sortList(mid)
+        # 合并
+        return self.merge(left, right)
+
+    def merge(self, left, right):
+        dummy = ListNode(0)
+        p = dummy
+        l = left
+        r = right
+
+        while l and r:
+            if l.val < r.val:
+                p.next = l
+                l = l.next
+                p = p.next
+            else:
+                p.next = r
+                r = r.next
+                p = p.next
+        if l:
+            p.next = l
+        if r:
+            p.next = r
+        return dummy.next
+
+作者：Junhao
+链接：https://leetcode.cn/problems/sort-list/solutions/215640/lc148-jian-ji-pythongui-bing-shi-xian-by-jhhuang/
+来源：力扣（LeetCode）
+著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。