Found and fixed a bug under 2 minutes

During Google Code Jam 2016 qualification round, while solving B-small, I was given 4 minutes after downloading the input file to submit the correct the output file. While trying to do so, I found that my code doesn't terminate for a case, I managed to find the bug and fix it under 2 minutes and avoided a penalty. I was surprised that I got correct answers for the sample test cases.