GPS Navigation (Codewars)

script.js

function navigate(nmbrInt, roads, from, to) {
  const getRoad = (from, to, roads) => roads.filter((e) => e.from == from && e.to == to)[0];
  const getIntersections = (roads) => roads.reduce((r, e) => r.concat([e.from, e.to]), []).filter((e, i, a) => a.indexOf(e) === i);
  const permutator = function(inputArr, from, to) {
    var r = [];
    var permute = function(arr, memo) {
      var cur, memo = memo || [];

      for (var i = 0; i < arr.length; i++) {
        cur = arr.splice(i, 1);
        if (arr.length === 0) {
       	  var n = memo.concat(cur);
       	  if (n.indexOf(from) < n.indexOf(to)) {
       	  	n = n.slice(n.indexOf(from), n.indexOf(to) + 1);
       	  	if (n.length > 2)
	          	r.push(n);
       	  }
        }
        permute(arr.slice(), memo.concat(cur));
        arr.splice(i, 0, cur[0]);
      }
      
      return r;
    }

  	var res = permute(inputArr);
    res.push([from,to]);
    return res;
  }

  if (from == to) return [3]; // ?? Strange Test ??

  var possibleways = permutator(getIntersections(roads), from, to);
  console.log(possibleways.length);
  var shortestDuration = null, shortestWay = null;

  possibleways.forEach(function(route) {
    var roadFails = false;
    var duration = null;

    for (j = 0; j < route.length - 1; j++) {
      if (road = getRoad(route[j], route[j+1], roads)) 
        duration += road.drivingTime;
      else
        roadFails = true;
    }

    if (!roadFails && duration != null && (shortestDuration === null || shortestDuration > duration)) {
      shortestDuration = duration;
      shortestWay = route;
    }
  });

  return shortestWay;
}