From f49b2e4a75c6f98c082923e1098aedc5cb27574b Mon Sep 17 00:00:00 2001
From: JaneyLin <105125897+janeyziqinglin@users.noreply.github.com>
Date: Mon, 6 Jun 2022 21:49:32 -0500
Subject: [PATCH] =?UTF-8?q?Update=200027.=E7=A7=BB=E9=99=A4=E5=85=83?=
 =?UTF-8?q?=E7=B4=A0.md?=
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the former code has not consider if nums is None or len(nums)==0
---
 problems/0027.移除元素.md | 38 ++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 21 deletions(-)

diff --git a/problems/0027.移除元素.md b/problems/0027.移除元素.md
index 4b50d666..b239136c 100644
--- a/problems/0027.移除元素.md
+++ b/problems/0027.移除元素.md
@@ -173,28 +173,24 @@ class Solution {
 
 Python：
 
-```python
+```python3
 class Solution:
-    """双指针法
-    时间复杂度：O(n)
-    空间复杂度：O(1)
-    """
-
-    @classmethod
-    def removeElement(cls, nums: List[int], val: int) -> int:
-        fast = slow = 0
-
-        while fast < len(nums):
-
-            if nums[fast] != val:
-                nums[slow] = nums[fast]
-                slow += 1
-
-            # 当 fast 指针遇到要删除的元素时停止赋值
-            # slow 指针停止移动, fast 指针继续前进
-            fast += 1
-
-        return slow
+    def removeElement(self, nums: List[int], val: int) -> int:
+        if nums is None or len(nums)==0: 
+            return 0 
+        l=0
+        r=len(nums)-1
+        while l<r: 
+            while(l<r and nums[l]!=val):
+                l+=1
+            while(l<r and nums[r]==val):
+                r-=1
+            nums[l], nums[r]=nums[r], nums[l]
+        print(nums)
+        if nums[l]==val: 
+            return l 
+        else: 
+            return l+1
 ```