Update power-of-four.cpp

Author: kamyu104

C++/power-of-four.cpp

@@ -1,11 +1,11 @@
-// Time:  O(logn)
-// Space: O(logn)
+// Time:  O(1)
+// Space: O(1)
 
 class Solution {
 public:
     bool isPowerOfFour(int num) {
         return num > 0 && (num & (num - 1)) == 0 &&
-               ((num & 0b101010101010101010101010101010101) == num);
+               ((num & 0b01010101010101010101010101010101) == num);
     }
 };