Power of Four

Desicription

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example 1:

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Input: 16
Output: true

Example 2:

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Input: 5
Output: false

Follow up: Could you solve it without loops/recursion?

Solution

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class Solution {
public:
bool isPowerOfFour(int num) {
return num > 0 && ((num & (num - 1)) == 0) && (num & 0x55555555) != 0;
}
};