// Quicksort built on lists, recursion and higher level pieces of the language.

fn quicksort(items) {
    if (len(items) < 2) {
        return items
    }
    let pivot = items[0]
    let less = []
    let greater = []
    var i = 1
    while (i < len(items)) {
        let current = items[i]
        if (current < pivot) {
            push(less, current)
        } else {
            push(greater, current)
        }
        i = i + 1
    }
    let result = quicksort(less)
    push(result, pivot)
    for (value in quicksort(greater)) {
        push(result, value)
    }
    return result
}

let data = [5, 3, 8, 1, 9, 2, 7, 4, 6, 0]
println("input:  " + str(data))
println("sorted: " + str(quicksort(data)))