import Foundation
let num = 42 // 00101010 in binary
// Convert number to binary string and count '1's
let binaryStr = String(num, radix: 2)
let bitCount = binaryStr.filter { $0 == "1" }.count
let result = bitCount % 2
print("0 = even number of bits set")
print("1 = odd number of bits set")
print("result: \(result)")
/*
run:
0 = even number of bits set
1 = odd number of bits set
result: 1
*/