[Shootout-list] Python Fannkuch using Loops

[Kevin Carson]

This is an implementation based on the reference code with little value add
from the Python language.

Kevin

#!/usr/bin/python -OO
# http://shootout.alioth.debian.org/
#
# Contributed by Kevin Carson

import sys

def fannkuch(n) :
    p = range(1, n+1)
    q = [None]*n
    maxflips = 0

    while True :
        if p[0] != 1 :
            q[0:n] = p[0:n]

            flips = 0
            while q[0] != 1 :
                k = q[0] - 1
                i = 0
                while i < k :
                    q[i],q[k] = q[k],q[i]
                    i += 1
                    k -= 1
                flips += 1

            if flips > maxflips :
                maxflips = flips

        j = k = 0
        for i in xrange(1, n) :
            if p[i - 1] < p[i] :
                j = i
            if (j != 0) and (p[i] > p[j-1]) :
                k = i

        if j == 0 :
            break

        p[j-1],p[k] = p[k],p[j-1]

        i = j
        j = n - 1
        while i < j :
            p[i],p[j] = p[j],p[i]
            i += 1
            j -= 1

    return maxflips


def main() :
    if len(sys.argv) == 2 :
        n = int(sys.argv[1])
    else :
        n = 1

    print "Pfannkuchen(%d) = %ld" % (n, fannkuch(n))

main()