添加0027移除元素 python3 版本

problems/0027.移除元素.md

@@ -253,6 +253,27 @@ class Solution:
                 
 ```
 
+``` python 3
+# 相向双指针法
+# 时间复杂度 O(n)
+# 空间复杂度 O(1)
+class Solution:
+    def removeElement(self, nums: List[int], val: int) -> int:
+        n = len(nums)
+        left, right  = 0, n - 1
+        while left <= right:
+            while left <= right and nums[left] != val:
+                left += 1
+            while left <= right and nums[right] == val:
+                right -= 1
+            if left < right:
+                nums[left] = nums[right]
+                left += 1
+                right -= 1
+        return left
+                
+```
+
 ### Go：
 
 ```go