Update binary-number-with-alternating-bits.py

Author: sfdye

binary-number-with-alternating-bits.py

@@ -4,5 +4,5 @@ def hasAlternatingBits(self, n):
         :type n: int
         :rtype: bool
         """
-        bits = bin(n)[2:]
-        return all(bits[i] != bits[i + 1] for i in range(len(bits) - 1))
+        a = n ^ (n >> 1)
+        return a & (a + 1) == 0