Problem Set 4: Forensics


  1. Watch Week 4’s lecture.

  2. Figure out whodunit.

  3. Resize some images.

  4. Recover some photos.

  5. Submit your code.

  6. Submit a form.


For help with Week 4 and Problem Set 4:

  • Watch Zamyla’s walkthroughs herein.

  • Take advantage of help50, eprintf, and debug50.

  • Start a discussion with classmates.

Getting Started

Alright, here we go again!

Log into and execute


within a terminal window to make sure your workspace is up-to-date.

Next, execute

mkdir ~/workspace/pset4/

at your prompt in order to make a directory called pset4 in your workspace directory.

Now execute

cd ~/workspace/pset4/

and your prompt should resemble the below.

~/workspace/pset4/ $

What to Do

  1. Implement Whodunit

  2. Implement either of:

  3. Implement Recover

How to Submit

Be sure you’ve signed up for a GitHub account, per Problem Set 0, and that you’ve logged into and authorized at least once, per Problem Set 1!

Step 1 of 2

  • Update your IDE:

  • Submit whodunit:

    cd ~/workspace/pset4/whodunit/
    submit50 cs50/2017/x/whodunit
  • Submit the less-comfortable version of resize (if you implemented it):

    cd ~/workspace/pset4/resize/
    submit50 cs50/2017/x/resize/less
  • Submit the more-comfortable version of resize (if you implemented it):

    cd ~/workspace/pset4/resize/
    submit50 cs50/2017/x/resize/more
  • Submit recover:

    cd ~/workspace/pset4/recover/
    submit50 cs50/2017/x/recover

Step 2 of 2

Submit this form!

This was Problem Set 4.