Jeffrey

Scores will be available on phone in Dec. 13, and online in Dec. 20.

Dhruv's explanation about this TM question in grecs wiki is correct. The similar question is question 94 in titaniumbits booklet.

In Dhruv's GRECS wiki, http://grecs.wikispaces.com/ , there is a TM question "Will this TM finish computing before sunset if it were to start before sunrise on the same day? ", which is said to be undecidable. I think the sentence is equivalent to " Will this TM accept a certain string within 'k' steps?" And I guess it's decidable, since it's very like "Will a TM halt within 'k' steps?" ,and maybe it's a subset of this one. The expression like "before sunset" which emphasizes time rather than "steps" is weird. Most of the textbooks and questions use "steps", since every step definied in a TM is a limited number of actions that can be done within a given time, which implies that "time" is equivalent to "step" in a sense. I've talked to Dhruv, and we want to get help from urch and experts. Just as he said, the CSGRE is notorious for asking questions that are slightly different from the ones you may already have encountered. So, "Will this TM finish computing before sunset if it were to start before sunrise on the same day? ", decidable or undecidable?

Hi, I'm preparing the data structures and algorithm. There are some books writen in C and some others in C++. Which one is better for the CS subject? C or C++? Those sample questions about algorithm are writen in C, right? Does it mean that the Object Oriented Programming part is not important? Thanks in advance:)