A program that identifies individual words in a sentence, stores these in a list and replaces each word with the position of that word in the list [closed]

Answer 1

Here's a linear algorithm:

position = {} # word -> position
words = sentence.split()
for word in words:
    if word not in position: # new word
       position[word] = len(position) + 1 # store its position
print(*map(position.__getitem__, words), sep=",")
# -> 1,2,3,4,5,6,7,8,9,1,3,9,6,7,8,4,5

The print() call uses Python 3 * syntax to unpack the result returned by map() that returns positions for the corresponding words here. See What does ** (double star) and * (star) do for parameters?