[eugenis]

I read the code just like reading an English article and then I saw the bug and fixed it right on spot. Then ran successfully. No print statements were added. Existing codes were not changed at all.

To give an example, one of the bug is for (int i = 0; i <= len; i++)

It is obvious so I just change <= to <.

[partisan]

Wow. OK. What makes you think this was the exact specific reason? Were there maybe other bugs you did not catch? Maybe there were less obvious things in the code that could have been fixed/changed? Is there any possibility of other factors?

I think the answer as to why this happened is in you. You just have to ask the right questions of yourself and answer honestly. Do some honest root cause analysis.

And then at the end of the day, there are those times where you do incredibly well and all seems as it should be and you don't get an offer. If there is absolutely nothing to learn from the experience, well then shrug and move on.

[amerkhalid]

Seems like not a good place to work at, if they didn't even design a proper problem that needs debugger to be solved. And expected you to use debugger.