dstaley

func partition<C: Comparable>(v: C[], left: Int, right: Int) -> Int {
    var i = left
    for j in (left + 1)..(right + 1) {
        if v[j] < v[left] {
            i++
            (v[i], v[j]) = (v[j], v[i])
        }
    }
    (v[i], v[left]) = (v[left], v[i])
    return i