Add code for leetcode 977 and update README.md.

Author: yanglr

Diff for: README.md

@@ -23,6 +23,10 @@ Python 玩转 LeetCode 的学习之路
 
 - [LeetCode面试系列 第10天：No.976 - 三角形的最大周长](http://www.justdopython.com/2019/11/20/leetcode976-largest-perimeter-triangle/)
 
+- [LeetCode面试系列 第12天：No.977 - 有序数组的平方](http://www.justdopython.com/2019/11/25/python-leetcode977-squares-of-a-sorted-array/)
+
+- [LeetCode面试系列 第11天：No.645 - 错误的集合](http://www.justdopython.com/2019/11/25/python-leetcode645-set-mismatch/)
+
 
 关注公众号：python技术，回复"python"一起学习交流
 

Diff for: leetcode-977/leetcode977.py

@@ -0,0 +1,13 @@
+from typing import List
+
+class Solution:
+    def sortedSquares(self, A: List[int]) -> List[int]:
+        B = sorted(A, key = abs) # sort by absolute values
+        res = list()
+        for elem in B:
+            res.append(elem*elem)
+        return res
+
+# below is testing        
+sol = Solution()
+print(sol.sortedSquares([-4,-2, 3,6]))