heapsort.groovy

/*
 * The Computer Language Shootout
 * http://shootout.alioth.debian.org/
 *
 * contributed by Jochen Hinrichsen
 */
public static final long IM = 139968
public static final long IA =   3877
public static final long IC =  29573

public static long last = 42

def gen_random(double max) {
    max * (last = (last * IA + IC) % IM) / IM
}

def heapsort(int n, double[] ra) {
    int l, j, ir, i
    double rra

    l = (n >> 1) + 1
    ir = n
    while (true) {
        if (l > 1) {
            rra = ra[--l]
        } else {
            rra = ra[ir]
            ra[ir] = ra[1]
            if (--ir == 1) {
                ra[1] = rra
                return
            }
        }
        i = l
        j = l << 1
        while (j <= ir) {
            if (j < ir && ra[j] < ra[j+1]) {
                ++j
            }
            if (rra < ra[j]) {
                ra[i] = ra[j]
                j += (i = j)
            } else {
                j = ir + 1
            }
        }
        ra[i] = rra
    }
}

def N = (args.length == 0) ? 1000 : args[0].toInteger()
def nf = java.text.NumberFormat.getInstance()
nf.setMaximumFractionDigits(10)
nf.setMinimumFractionDigits(10)
nf.setGroupingUsed(false)
double []ary = (double[]) java.lang.reflect.Array.newInstance(double.class, N+1)
for (i in 0..<N) {
    ary[i] = gen_random(1)
}
heapsort(N, ary)
println nf.format(ary[N])