box-o-sand/intro-to-algorithms/ch02.py

from __future__ import print_function

import os
import random
import timeit


DEBUG = os.environ.get('DEBUG') == '1'


def debug(msg):
    if DEBUG:
        print(msg)


def insertion_sort(arr):
    debug('BEGIN')
    for j in range(1, len(arr)):
        key = arr[j]
        i = j - 1
        debug('FOR:\tj={}, key={}, i={}'.format(j, key, i))

        while i > -1 and arr[i] > key:
            arr[i + 1] = arr[i]
            debug('WHILE:\tset: arr[{}] = {}'.format(i + 1, arr[i]))
            i = i - 1

        arr[i + 1] = key
        debug('FOR:\tset: arr[{}] = {}'.format(i + 1, key))

    debug('END')
    return arr


def main():
    for power in range(1, 5):
        to_sort = list(range(10 ** power))
        to_sort_sorted = to_sort[:]
        to_sort_reversed = list(reversed(to_sort[:]))

        for i in range(3):
            random.shuffle(to_sort)

        for arr, desc in (
            (to_sort_sorted, 'sorted'),
            (to_sort, 'shuffled'),
            (to_sort_reversed, 'reversed')):

            timing = timeit.timeit(
                lambda: insertion_sort(arr),
                number=10
            )
            print('{} {}: {}'.format(10 ** power, desc, timing))


if __name__ == '__main__':
    main()