0(n) runtime string reverse

reverse.py

# 0(n) runtime
# Only needs to move up to half the way of the list in order to shuffle things around.
# Something fast would be a merge sort with a key that knows the new order

words = 'hello world'
# Create to a List of the words and get the length as an Int.
# We don't actually need to cast it to a List in Python.
# Indexing Strings in Python works like a List.
lst = list(words)
length = len(lst)
for index, x in enumerate(lst):
    if index >= length / 2:
        # if we're at half way or more break - we've swapped everything
        break
    # Pull out this value
    swap = lst[index]
    # Move the end value to the value we just pulled out
    lst[index] = lst[length - max(index + 1, 1)]
    # Pop the value in swap into the end value we just moved
    lst[length - max(index + 1, 1)] = swap

print lst