import Foundation
func countSetBits(_ n: Int) -> Int {
var count = 0
var num = n
while num > 0 {
count += num & 1
num >>= 1
}
return count
}
let num = 445; // 0001 1011 1101
print("The number of set bits in \(num) is \(countSetBits(num))")
/*
run:
The number of set bits in 445 is 7
*/