Infosys Specialist Programmer interview questions

Interviewer: seeing my resume, so you are good at coding!! Me: yeah!:) Interviewer: took a question booklet and asked to write code for it in 30 min Question read: You are given a subset-M of tourist places among N-places in a city along with how these places are connected with distance between them. Now you being a traveller, task is to reduce the total distance travelled to cover all places in M and print minimum total distance. Me: :-! Started implementing basic class with adjacency matrix and thinking about djikistra!!?? TSP?? answer was no!! And it suddenly flashed me how about minimum spanning tree and then I used prim's concept to write a function for it.:-/ Interviewer: ( without checking code :( ) what's minimum spanning tree??