Databases
StackOverflow2013
Postsdbo
POCreating a travelling salesman program, is permutations a good technique?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POCreating a travelling salesman program, is permutations a good technique?
    primarykey
    data
    text
    <p>I am trying to get my head around a TSP program for college, I have to admit I'm finding it very difficult.</p> <p>Basically I have an array of Lat values and an array of Lng values, using haversine's, I have transferred the distances into a matrix.<br> Now where to go from here?<br> I have to find the shortest distance, visiting all 80 towns. I am trying to think of the best way to do it. Should I make a nearest neighbor algorithm? Should I just store the permutations and total the distance. or is there a better way? I have to admit, I think this is a little difficult for a 1st year student! Anyway here's my code, it's awful, the applet etc was given to us.</p> <pre><code>public class Brain { //These are the names of the 80 towns and their north and west GPS co-ordinates static double north[] = {53.855,52.794,54.350,53.433,52.992,54.117,53.328,54.800,54.863,55.071,54.502,54.343,51.746,54.660,51.680,54.597,53.091,53.175,55.136,52.831,53.976,53.944,53.861,53.991,51.622,52.354,51.897,54.996,54.322,53.714,53.348,54.009,54.500,52.085,53.345,52.846,52.502,54.345,53.272,52.677,53.728,53.106,52.648,52.059,51.708,53.783,54.851,54.957,55.053,52.665,52.447,53.727,53.197,51.904,54.750,52.131,53.382,52.266,54.248,53.116,53.522,52.863,52.396,54.210,52.451,54.590,53.633,52.714,54.267,53.245,54.830,52.679,52.474,52.268,53.515,53.267,52.257,53.800,52.334,51.952}; static double west[] = {-6.538,-6.165,-6.655,-7.950,-6.987,-9.167,-8.219,-7.790,-6.284,-6.508,-8.190,-6.260,-8.735,-5.670,-9.453,-5.930,-7.913,-6.525,-7.456,-6.932,-6.719,-8.095,-9.299,-7.360,-8.886,-7.712,-8.470,-7.307,-5.703,-6.350,-6.260,-6.405,-6.770,-7.640,-7.051,-8.981,-6.566,-7.640,-9.049,-6.292,-6.878,-6.065,-7.256,-9.507,-8.531,-8.917,-5.811,-7.720,-6.946,-8.624,-9.486,-7.800,-8.567,-8.957,-6.610,-8.642,-6.591,-8.270,-6.971,-7.324,-7.338,-8.200,-6.945,-5.882,-9.055,-7.290,-8.183,-8.869,-8.483,-9.306,-7.470,-7.814,-8.162,-9.696,-8.851,-7.500,-7.129,-9.533,-6.458,-7.846}; String names[] = {"Ardee","Arklow","Armagh","Athlone","Athy","Ballina","Ballinasloe","Ballybofe","Ballymena","Ballymoney","Ballyshannon","Banbridge","Bandon","Bangor","Bantry","Belfast","Birr","Blessington","Buncrana","Carlow","Carrickmacross","Carrick-On-Shannon","Castlebar","Cavan","Clonakilty","Clonmel","Cork","Derry","Downpatrick","Drogheda","Dublin","Dundalk","Dungannon","Dungarvan","Edenderry","Ennis","Enniscorthy","Enniskillen","Galway","Gorey","Kells","Kilcoole","Kilkenny","Killarney","Kinsale","Knock","Larne","Letterkenny","Limavady","Limerick","Listowel","Longford","Loughrea","Macroom","Magherafelt","Mallow","Maynooth","Mitchelstown","Monaghan","Mountmellick","Mullingar","Nenagh","New-Ross","Newcastle","Newcastle-West","Omagh","Roscommon","Shannon","Sligo","Spiddal","Strabane","Thurles","Tipperary","Tralee","Tuam","Tullamore","Waterford","Westport","Wexford","Youghal"}; static double[][] matrix = new double[80][80]; boolean visit[]=new boolean[80]; boolean valid = true; public static void fillmatrix (){ double tote = 0; for(int i=1;i&lt;80;i++){ for(int j=1;j&lt;80;j++){ matrix[i][j]=getDistance(north[i],west[j],north[j],west[j]); } } } public String compute () { String solution =""; for (int i=0;i&lt;80;i++){ solution+=(char)(i+40); } solution+="Anything you add on after the 80 characters will be " + "printed in the textbox (e.g. you can compute the distance)"; return solution; } public static double getDistance(double lat1, double lon1, double lat2, double lon2){ double R = 6371; double dLat = Math.toRadians((lat2-lat1)); double dLon = Math.toRadians((lon2-lon1)); double a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * Math.sin(dLon/2) * Math.sin(dLon/2); double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); double d = R * c; return d; } } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USTimmy O'Mahony
    1. USLeah Buchanan
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POCreating a travelling salesman program, is permutations a good technique?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POCreating a travelling salesman program, is permutations a good technique?
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    3. VO
      singulars
      1. POCreating a travelling salesman program, is permutations a good technique?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COif there are 80 cities that means there are approximately 80! (10^ 118) permutations!
      singulars
      1. POCreating a travelling salesman program, is permutations a good technique?
      1. USColin D
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload