Determine if a given integer is a power of two. A number is a power of two if it can be expressed as 2 raised to some non-negative integer (e.g., 1, 2, 4, 8, 16, 32, ...). Return true if the number is a power of two, false otherwise.

Examples:

Input: num = 1 Output: true Explanation: 1 is 2^0, which is a power of two Input: num = 16 Output: true Explanation: 16 is 2^4, which is a power of two Input: num = 18 Output: false Explanation: 18 cannot be expressed as 2 raised to any integer Input: num = 0 Output: false Explanation: Zero is not a power of two Input: num = -4 Output: false Explanation: Negative numbers cannot be powers of two
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