Update 7-Reverse-Integer.py

Author: neetcode-gh

7-Reverse-Integer.py

@@ -1 +1,22 @@
+class Solution:
+    def reverse(self, x: int) -> int:
+        # Integer.MAX_VALUE = 2147483647 (end with 7)
+        # Integer.MIN_VALUE = -2147483648 (end with -8 )
 
+        MIN = -2147483648 # -2^31, 
+        MAX = 2147483647  #  2^31 - 1
+
+        res = 0
+        while x:
+            digit = int(math.fmod(x, 10))   # (python dumb) -1 %  10 = 9
+            x = int(x / 10)                 # (python dumb) -1 // 10 = -1
+            
+            if (res > MAX // 10 or 
+                (res == MAX // 10 and digit >= MAX % 10)):
+                return 0
+            if (res < MIN // 10 or 
+                (res == MIN // 10 and digit <= MIN % 10)):
+                return 0
+            res = (res * 10) + digit
+
+        return res