Update solution 007 [Python3]

Author: chakyam

solution/007.Reverse Integer/README.md

@@ -0,0 +1,20 @@
+class Solution:
+    def reverse(self, x):
+        """
+        :type x: int
+        :rtype: int
+        """
+        if x==0:
+            return 0
+        y=str(abs(x))
+        y=y[::-1]
+        y=int(y)
+        if x<0:
+            tmp=-y
+        else:
+            tmp=y
+        
+        if tmp>=2**31-1 or tmp<-(2**31):
+            return 0
+        else:
+            return tmp