Merge pull request Jack-Lee-Hiter#1 from Sen1992/master

你可以看一下

Author: Jack-Lee-Hiter

Target Offer/不用加减乘除做加法.py

@@ -6,13 +6,24 @@
 # 可能是python的的整型可以无限大的原因, 导致正数和负数的异或操作不断变成更小的负数而不会溢出
 # 使用Swift尝试了一下, 还是可以求得正数和负数的位操作相加运算的
 # -*- coding:utf-8 -*-
+# class Solution:
+#     def Add(self, num1, num2):
+#         while num2:
+#             sum = num1 ^ num2
+#             carry = (num1 & num2) << 1
+#             num1 = sum
+#             num2 = carry
+#         return num1
+# s = Solution()
+# print(s.Add(4, 2))
+# -*- coding:utf-8 -*-
+# 通过每次对num1进行与操作保证是一个32位的整形
+# 因此最后我们可以判断符号位是否为1做处理
 class Solution:
     def Add(self, num1, num2):
-        while num2:
-            sum = num1 ^ num2
-            carry = (num1 & num2) << 1
-            num1 = sum
-            num2 = carry
-        return num1
-s = Solution()
-print(s.Add(4, 2))
+        # write code here
+        while num2 != 0:
+            temp = num1 ^ num2
+            num2 = (num1 & num2) << 1
+            num1 = temp & 0xFFFFFFFF
+        return num1 if num1 >> 31 == 0 else num1 - 4294967296