reverse sentence

reverse_sentence.py

#!/usr/bin/env python
# encoding: utf-8

import array


def reverse_array(letters, start, end):

    while start < end:

        letters[start], letters[end] = letters[end], letters[start]

        start += 1
        end -= 1


def reverse_sentence(sentence):

    a = array.array('c', sentence)

    reverse_array(a, 0, len(a) - 1)

    start = end = 0

    while end < len(a):

        if a[end] not in (' ', ','):
            end += 1
            continue

        reverse_array(a, start, end-1)

        end += 1
        start = end

    reverse_array(a, start, end-1)

    return a.tostring()


def reverse_sentence_with_stack(sentence):

    sentence = sentence.split(' ')

    reversed = []

    while sentence:

        reversed.append(sentence.pop(-1))

    return ' '.join(reversed)


print reverse_sentence('test is test, that is true')

print reverse_sentence_with_stack('test is test, that is true')