Power of Four
Desicription
Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
Example 1:
代码语言:javascript复制Input: 16
Output: true
Example 2:
代码语言:javascript复制Input: 5
Output: false
Follow up: Could you solve it without loops/recursion?
Solution
代码语言:javascript复制class Solution {
public:
bool isPowerOfFour(int num) {
return num > 0 && ((num & (num - 1)) == 0) && (num & 0x55555555) != 0;
}
};