I submitted #Greedy and it was marked as wrong by #edx on a bunch of the criteria. I ran the program myself after and I get the correct answer for the criteria. Is this normal?

  • 2
    No, it's not. Probably you're not realizing that your program is not giving the correct output. Maybe try updating your question with the link at the end of check50's output!
    – kzidane
    Apr 2, 2015 at 16:02

1 Answer 1


This is a common question from those (myself included) who feel they have the right output, especially with the early exercises. For instance, an output might state the coins needed to make change. While the number of coins may be right, the output may not be formatted correctly. You should also be thinking that CHECK50 has been tested with thousands of students now, so it's a safe bet that it really is working correctly. A big lesson that we all learn is that the output has to match the program specification exactly and precisely. That means no extra line feeds, no extra words, no extra anything, and exactly everything that's asked for. Always make sure that the output is precisely what was specified.

Here's a useful tip - run the staff sample programs and compare their output to your program's output. What is different? If anything is different, that should be a roadmap to what you need to change. Remember, these assignments are about meeting the exact spec. Improvements are something you can do later in a consultation with the client. ;-) Hope this helps.

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