Solve : Reverse Bits

Author: printjin-gmailcom

reverse-bits/printjin-gmailcom.py

@@ -1,6 +1,8 @@
 class Solution:
     def reverseBits(self, n):
-        b = bin(n)[2:]              
-        b = b.zfill(32)             
-        reversed_b = b[::-1]        
-        return int(reversed_b, 2) 
+        n = (n >> 16) | (n << 16)
+        n = ((n & 0xff00ff00) >> 8) | ((n & 0x00ff00ff) << 8)
+        n = ((n & 0xf0f0f0f0) >> 4) | ((n & 0x0f0f0f0f) << 4)
+        n = ((n & 0xcccccccc) >> 2) | ((n & 0x33333333) << 2)
+        n = ((n & 0xaaaaaaaa) >> 1) | ((n & 0x55555555) << 1)
+        return n