update status/code Array/remove-element.py

Author: yennanliu

README.md

@@ -87,7 +87,7 @@
 016 | [3 Sum Closest](https://leetcode.com/problems/3sum-closest/) | [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/3sum-closest.py) | _O(n^2)_   | _O(1)_  | Medium |`Two Pointers`, `basic`, `trick`| AGAIN**
 018| [4 Sum](https://leetcode.com/problems/4sum/) | [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/4sum.py)   | _O(n^3)_  | _O(1)_    | Medium  | `k sum`, `Two Pointers`, `trick`, `hard` | AGAIN (not start)
 026 | [Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/)|  [Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/remove-duplicates-from-sorted-array.py) | _O(n)_   | _O(1)_  | Easy   | `Two Pointers`, `basic`, `trick` |  AGAIN*
-027 | [Remove Element](https://leetcode.com/problems/remove-element/) | [Python](./Python/remove-element.py) | _O(n)_      | _O(1)_         | Easy           ||
+027 | [Remove Element](https://leetcode.com/problems/remove-element/) |[Python](https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Array/remove-element.py) | _O(n)_  | _O(1)_ | Easy  |`basic`| AGAIN* 
 031 | [Next Permutation](https://leetcode.com/problems/next-permutation/)| [Python](./Python/next-permutation.py) | _O(n)_  | _O(1)_          | Medium   | Tricky | 
 048 | [Rotate Image](https://leetcode.com/problems/rotate-image/)   | [Python](./Python/rotate-image.py) | _O(n^2)_      | _O(1)_         | Medium         ||
 054 | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix/) | [Python](./Python/spiral-matrix.py) | _O(m * n)_    | _O(1)_         | Medium         ||

leetcode_python/Array/remove-element.py

@@ -6,29 +6,70 @@
 # The order of elements can be changed. It doesn't matter what you leave beyond the new length.
 #
 
+# V0 
 
-# V1 : dev (?)
-
-
-class Solution:
+# V1 
+# https://blog.csdn.net/coder_orz/article/details/51578854
+# IDEA : DOUBLE POINTER 
+class Solution(object):
     def removeElement(self, nums, val):
-        return [ k for k in nums if k != val]
-    
-
-# V2 
-
+        """
+        :type nums: List[int]
+        :type val: int
+        :rtype: int
+        """
+        length = 0
+        for i in range(len(nums)):
+            if nums[i] != val:
+                nums[length] = nums[i]
+                length += 1
+        return length
+        
+# V1' 
+# https://blog.csdn.net/coder_orz/article/details/51578854
 class Solution(object):
     def removeElement(self, nums, val):
-        for x in nums[:]:
-            if x == val:
-                nums.remove(x)      
-        return len(nums)
-     
-
+        """
+        :type nums: List[int]
+        :type val: int
+        :rtype: int
+        """
+        rm_index = []
+        for i in range(len(nums)):
+            if nums[i] == val:
+                rm_index.append(i)
+        last = len(nums) - 1
+        for i in rm_index:
+            while last >= 0 and nums[last] == val:
+                last -= 1
+            if last < 0:
+                break
+            nums[i] = nums[last]
+            last -= 1
+        return len(nums) - len(rm_index)
 
+# V1'' 
+# https://blog.csdn.net/coder_orz/article/details/51578854
+class Solution(object):
+    def removeElement(self, nums, val):
+        """
+        :type nums: List[int]
+        :type val: int
+        :rtype: int
+        """
+        length, i = len(nums), 0 
+        while i < length:
+            if nums[i] == val:
+                nums[i] = nums[length - 1]
+                length -= 1
+            else:
+                i += 1
+        return length
 
-# V3    
-class Solution:
+# V2 
+# Time:  O(n)
+# Space: O(1)
+class Solution(object):
     # @param    A       a list of integers
     # @param    elem    an integer, value need to be removed
     # @return an integer
@@ -40,8 +81,4 @@ def removeElement(self, A, elem):
                 last -= 1
             else:
                 i += 1
-        return last + 1
-
-
-
-
+        return last + 1