Check whether an integer is a power of two

Given a signed 32-bit integer `n`, return `true` if `n` is an exact power of 2, otherwise return `false`. A power of 2 is a number of the form `2^k` where `k >= 0` (e.g., 1, 2, 4, 8, 16, ...). ## Input - `n`: an integer in the range `[-2^31, 2^31 - 1]` ## Output - Boolean indicating whether `n` is a power of 2. ## Examples - `n = 1` → `true` (2^0) - `n = 16` → `true` (2^4) - `n = 3` → `false` - `n = 0` → `false` - `n = -8` → `false` ## Follow-up - Aim for an `O(1)` / bit-manipulation solution (no loops over bits, and no precomputed set/table of powers).