Dots

Background

In the competitive world of data compression, a startup called Dot Decode Inc. believed they had a game-changing algorithm. Their method, developed by the eccentric Dr. Dot, used dots to indicate character positions within a string. Each dot before a character represented its index. For example, "...5.C..S....0" would decode to "CS50". Dr. Dot has vanished, leaving behind only an encoded message. The company's future depends on cracking his code. Can you write a program to decode these messages and help solve the mystery of Dr. Dot's disappearance?

Understanding

In a file called dots.py, implement a program that takes a jumbled, encoded message consisting of letters and periods and prints the decoded message, where the position of each letter in the decoded message is equal to the number of periods before it in the encoded message for example:

[!NOTE] The indexes are starting from 1!

The input ...5.C..S....0, has output CS50

...5 means that the character 5 has the position number 3 in the string.

.C means that the character C has the position number 1 in the string.

..S means that the character S has the position number 2 in the string.

....0 means that the character 0 has the position number 4 in the string.

You can assume that there will be no 0 indexes letters, no repeated indexes.

The decoding algorithm should be coded inside the decode function. The function should accept a string, then return the decoded version of it.

Before You Begin

Execute cd by itself in your terminal window. You should find that your terminal window’s prompt resembles the below:

Next execute

1	`mkdir dots`

to make a folder called dots in your codespace.

Then execute

cd dots

to change directories into that folder.

You should now see your terminal prompt as dots/ . You can now execute

1	`code dots.py`


to make a file called

dots.py` where you’ll write your program.

Specification

Use this code as a template. Edit only the body of decode:

def main():

    text = input(": ")
    print(decode(text))

def decode(text):
    raise NotImplementedError

if __name__ == "__main__":
    main()

Hints

More about functions: https://docs.python.org/3/tutorial/controlflow.html#defining-functions

More about lists: https://docs.python.org/3/tutorial/datastructures.html#more-on-lists

More about dictionaries: https://docs.python.org/3/tutorial/datastructures.html#dictionaries

How to Test

Run your program with python dots.py. Your program should ask for input. Type in ..o...t.d and press Enter. Your program should output dot.
Run your program with python dots.py. Type ....k..u.d...c.....y and press Enter. Your program should output:
```
ducky
```
Run your program with python dots.py. Type ..S.C...5....0 and press Enter. Your program should output:
```
CS50
```
Run your program with python dots.py. Type ......,.....o...l..e................y............... ..........w.............r....l..............e.........o........h....... .................o...................?..................u............a........... .H and press Enter. Your program should output:
```
Hello, how are you?
```

If you run into an error saying your file cannot be opened, retrace your steps to be sure that you are inside your dots folder and have saved your dots.py file there.

If you get an error saying python is not found, try replacing it with python3 in the terminal command instead.

You can execute the below to check your code using check50, a program that CS50 will use to test your code:

1	`check50 alum-challenges/problems/main/python/week-2/dots/tests`

* Green smiles mean your program has passed a test! * Red frowns will indicate your program output something unexpected. * Orange neutral faces mean you must fix the failed check before those checks can run.

Visit the URL that check50 outputs to see the input check50 handed to your program, what output it expected, and what output your program actually gave.

How to Submit

Coming soon