added daily challenge

Author: Pasindu-Vishmika

231. Power of Two.py

@@ -0,0 +1,7 @@
+class Solution:
+    def isPowerOfTwo(self, n: int) -> bool:
+        while n > 1:
+            if n % 2 != 0:
+                return False
+            n = n // 2
+        return n == 1