You need to make sure your Lab 3 implementation is correct before starting Lab 4. Like all previous labs, you can use the late grader ( instructions here) to submit your lab as many times as you want until you get a perfect grade. Normally, your late grade does not affect the actual grade that we use to evaluate your performance at the end of the semester. However, to encourage you to fix your mistakes in Lab 3 and Lab 4, we will use the following formula for your Lab 3 and Lab 4 grades.
Lab 3 or 4 grade = Maximum(initial grade, 0.6 * initial grade + 0.4 * late grade)
In other words, if you choose to improve your Lab 3 or Lab 4 grades using the late grader, we will use your late grade for 40% of your grades.
We really encourage everyone to improve their lab 3 and lab 4 to achieve a score of 100 before continuing to work on future labs. However, note that Passing all the tests does not mean that your lab is correct! An incorrect program may just happen to behave correctly on our test cases. It is your responsibility to ensure that your labs are correct.