#!/usr/bin/env python
from random import randint

def bitonic_sort(up, x):
    if len(x) <= 1:
        return x
    else:
        half = int(len(x) / 2)
        first = bitonic_sort(True, x[:half])
        second = bitonic_sort(False, x[half:])
        return bitonic_merge(up, first + second)

def bitonic_merge(up, x):
    # assume input x is bitonic, and sorted list is returned
    if len(x) == 1:
        return x
    else:
        bitonic_compare(up, x)
        half = int(len(x) / 2)
        first = bitonic_merge(up, x[:half])
        second = bitonic_merge(up, x[half:])
        return first + second

def bitonic_compare(up, x):
    dist = int(len(x) / 2)
    for i in range(dist):
        if (x[i] > x[i + dist]) == up:
            x[i], x[i + dist] = x[i + dist], x[i] #swap

if __name__ == '__main__':
   sorted_array = bitonic_sort(True, [randint(1,1000) for i in range(16)])
   print(sorted_array)