191 Number of 1 Bits update solution

Author: doh6077

number-of-1-bits/doh6077.py

@@ -1,4 +1,7 @@
 class Solution:
     def hammingWeight(self, n: int) -> int:
-        binary_num = format(n, 'b')
-        return binary_num.count('1')
+        ans = 0 
+        while n != 0:
+            ans += 1
+            n = n & ( n-1)
+        return ans