JS-solution to: https://tausiq.wordpress.com/2013/08/08/uab-2005-problem-6-shortest-path-in-alabama/

routes_in_alabama.js

/*
  JS-solution to:
  https://tausiq.wordpress.com/2013/08/08/uab-2005-problem-6-shortest-path-in-alabama/
*/
var getRoutes = (function(){

  var rawData = [
    'Alabaster-Birmingham 24 miles',
    'Alabaster-Montgomery 71 miles',
    'Birmingham-Huntsville 103 miles',
    'Birmingham-Tuscaloosa 59 miles',
    'Demopolis-Mobile 141 miles',
    'Demopolis-Montgomery 101 miles',
    'Demopolis-Tuscaloosa 65 miles',
    'Mobile-Montgomery 169 miles',
    'Montgomery-Tuscaloosa 134 miles'
  ];

  // transform raw data into towns and distances
  var towns = [], dists = [];
  rawData.forEach(function(x){
    x = x.split(' ');
    var y = x[0].split('-');
    towns.indexOf(y[0]) < 0 && towns.push(y[0]);
    towns.indexOf(y[1]) < 0 && towns.push(y[1]);
    dists.push([y[1],y[0],x[1]/1]);
    dists.push([y[0],y[1],x[1]/1]);
  });
  towns = towns.sort();
  window.towns = towns; // export just for test gui


  // find all routes
  var routes = [], routemem = towns.slice(), routemem2, one;
  // add zero distance routes (to-from same city)
  towns.forEach(function(town){
    routes.push([0,town,town]);
  });
  // add all other routes
  do {
    routemem2 = [];
    towns.forEach(function(town){
      routemem.forEach(function(route){
        route = route.push ? route : [route];
        dists.forEach(function(dist){
          if(
            dist[0] == route[route.length-1] &&
            dist[1] == town &&
            route.indexOf(town) < 0
          ){
            one = route.concat(town);
            if(one[0]/1 != one[0]){one.unshift(0);}
            one[0] += dist[2];
            routemem2.push(one);
          }
        });
      });
    });
    routemem = routemem2;
    routes = routes.concat(routemem);
  } while (routemem2.length);

  // order routes (shortest to longest)
  routes.sort(function(x,y){
    return x[0] < y[0] ? -1 : 1;
  });

  // get all routes between two cities (shortest first)
  return function(from,to){
    return routes.filter(function(x){
      return x[1] == from && x[x.length-1] == to;
    }).map(function(x){
      x = x.slice();
      var miles = x.shift();
      return {route:x.join('-'),distance:miles + ' miles'};
    });
  }
  
})();



// Small GUI to test the solution 

var selects = ' from <select id="from"><option value="">-</option>';
towns.forEach(function(town){
  selects += '<option value="' + town + '">' + town + '</opton>';
});
selects += '</select>';
selects += selects.split('from').join('to');
html = '<h1>Route planner</h1><p>Travel ' + selects +
  '</p><p id="result"></p>';
document.write(html);

function d(x){return document.getElementById(x);}
var from = d('from'), to = d('to'), result = d('result');
[from,to].forEach(function(x){
  x.addEventListener('change',showResult);
});

function showResult(){
  var r = getRoutes(from.value,to.value).map(function(x){
    return '<span style="display:inline-block;width:600px">' +
      x.route + '</span>' + x.distance;
  });
  r.length && r.unshift('<strong>Shortest route:</strong>');
  r.length>2 && r.splice(2,0,"<br><strong>Other routes:</strong>");
  result.innerHTML = r.join("<br>");
}