I initially applied online. Recruiters from the company were heading to our school, so I was set up with an interview upon their arrival in early March.

There were three interviewers present that day: one main interviewer and two others. I was interviewed by one of the secondary interviewers, but halfway through, the main interviewer came in and took over. The interview was entirely technical.

The first interviewer asked about matrix coding in my preferred language (Java), then asked me to do more with it and improve the code. He then asked about the running times of the two pieces of code.

The other, main, interviewer wrote sample code in C and asked me to explain it and answer related questions. I had no prior experience in C, which I had already disclosed to him. To this, he replied, "excellent." The interview lasted approximately one hour.

I heard nothing from them until three weeks later. I attribute this delay to the fact that they returned to New York City, and then my area experienced a significant snowstorm.

I received a call about a second interview. At this interview, the same main interviewer from before interviewed me again. This was another technical interview where I was asked to write a piece of code with a finance twist in my language of choice. At the end, I was immediately asked to return the next day for a third interview. This interview also lasted approximately one hour.

The third interview actually consisted of two separate interviews: first with a senior member, and then with an HR representative. These were not technical interviews.

The senior member presented me with a real-world problem and asked what steps I would take to solve it. The HR representative was mainly present, in my opinion, to observe the interviewees' personalities. Both interviews combined lasted approximately 40 minutes.

I did not receive word for another two weeks. At that point, I was informed via phone and email that I had been accepted, but there were no training positions open. Approximately a week passed before I was given an official offer, as a spot had become available.

Write a program that, given a 2D integer matrix (default value: 0) and a coordinate within the matrix, sets all elements diagonal to the coordinate to a value of 1. This will result in an 'X' shape on the matrix with the given coordinate at its center.

Improve upon the previous code, then provide the running time for both codes. Explain which would be preferable to use if you were a manager presented with these two codes and why.