Answer for challenge #3 in http://140swift.tumblr.com

groupedStrings

@140Swift
let s = ["abeforth", "albus", "bagshot", "bellatrix", "black"]
let groupedStrings: [[String]] = {
    var r:[[String]]=[]
    var n = [s[0]]
    for (i,v) in enumerate(s) {
        if i != 0 {
            if (String(Array(v)[0]) == String(Array(n[n.count-1])[0])) {
                n.append(v)
            } else {
                r.append(n)
                n.removeAll(keepCapacity: false)
                n.append(v)
            }
        }
    }
    r.append(n)
    return r
}()