Checkpoint: Debug & Repair Lab
Separate true reports from lies, fix the real defect, and leave behind an exhaustive regression net.
The repair lab - reproduce, hypothesize, fix, and prove the fix.
Inside the provided Solution skeleton, repair changeFor per the
checkpoint. Two defects hide in the customer reports: one is real
(negative input flows into % and prints negative coin counts), one is a
lie (41 cents is actually miscounted in a sneakier way - your exhaustive
0..99 sweep in the tests is what catches arithmetic bugs a few spot
checks never will).
Method reminder: reproduce first, form one hypothesis at a time, fix the cause, then add the test that would have caught it. The third test block is that test - it reconstructs every amount from its coin breakdown, so any future regression in the coinage logic fails loudly.