binarygap.swift

public func solution(N : Int) -> Int {
    let bytes = String(N, radix: 2)
    var max = 0
    var current = 0

    for n in bytes.characters {
        if n == "0" {
            current += 1
        } else {
            if current > max {
                max = current
            }
            current = 0
        }
    }

    return max
}