題目連結: https://leetcode.com/problems/reverse-bits/
參考解法: https://leetcode.com/problems/reverse-bits/discuss/1583277/Swift-Bit-manipulation-with-explanation
func reverseBits(_ n: Int) -> Int {
var tmp = n
var result = 0
for _ in 1 ... 32 {
let val = tmp & 1
result = result << 1 + val
tmp = tmp >> 1
}
return result
}