Travelling salesman problem extension

Hello. I've been looking for this for long time. My problems is related with TSP, but at the same time it's really doesn't. Would it be able to set the number of cities that has to be visited out of all cities. For example : We have 80 cities spreaded around. Out of all 80 we have to connect only 40 towns in loop. Also the task is to join them as so that between each citie there is 40 km or units (units would be used if we do not know exact lenght between cities and when we use (x,y) for city location.

If you know how to make that, I would be very please.

The code : http://codepad.org/vxdGzCdu

Thank you!

Looks just like the code you found here -> looking for detailed version of traveling salesman problem - C++ | DaniWeb (from Sept 2010)

And which you bumped (with no cigar) yourself.
So tell me, in the last 14 days, have you actually done any more work for yourself on the problem, or are you just going to keep wandering from forum to forum copy/pasting your message?

Because if all you've done is sit on your arse hoping for someone else to post your homework answer, then failure is well deserved.