E3

src/Tour.cpp

@@ -52,7 +52,7 @@ void Tour::draw(QGraphicsScene *scene) const {
         return;
 
     Node *node = m_startNode;
-    do{
+    do {
         node->point.draw(scene);
         node->point.drawTo(node->next->point, scene);
         node = node->next;
@@ -116,6 +116,31 @@ void Tour::insertNearest(Point p) {
     nearest->next = newNode;
 }
 
+Node *findbestNodeTSP(Node *const start, Point &point) {
+    auto calcHeuristic = [&point](Node *const insertAt) -> double {
+        double distanceWithNewPoint = insertAt->point.distanceTo(point) +
+                                      point.distanceTo(insertAt->next->point);
+        double originalDistance = insertAt->point.distanceTo(insertAt->next->point);
+
+        return distanceWithNewPoint - originalDistance;
+    };
+
+    double optimalH = Q_INFINITY;
+    Node *optimalNode;
+
+    Node *node = start;
+    do {
+        double h = calcHeuristic(node);
+        if (h < optimalH) {
+            optimalH = h;
+            optimalNode = node;
+        }
+        node = node->next;
+    } while (node != start);
+
+    return optimalNode;
+}
+
 void Tour::insertSmallest(Point p) {
     if (m_startNode == nullptr) {
         m_startNode = new Node(p);
@@ -128,21 +153,7 @@ void Tour::insertSmallest(Point p) {
         return;
     }
 
-    Node *bestNode = m_startNode;
+    Node *bestNode = findbestNodeTSP(m_startNode, p);
-    double minIncrease = Q_INFINITY;
-
-    Node *node = m_startNode;
-    do {
-        double increase = node->point.distanceTo(p) +
-                          p.distanceTo(node->next->point) -
-                          node->point.distanceTo(node->next->point);
-        if (increase < minIncrease) {
-            minIncrease = increase;
-            bestNode = node;
-        }
-        node = node->next;
-    } while (node != m_startNode);
-
     auto *newNode = new Node(p, bestNode->next);
     bestNode->next = newNode;
 }

src/tsp.cpp

@@ -18,7 +18,7 @@
 int main(int argc, char *argv[]) {
     QApplication a(argc, argv);
 
-    string filename = "tsp10.txt";
+    string filename = "tsp1000.txt";
 #ifdef __APPLE__
     // On macOS the resources are copeied to build/<release-target>/
     // whilst, the running binary is under build/<release-target>/TSP.app/Contents/MacOS/
@@ -46,22 +46,25 @@ int main(int argc, char *argv[]) {
     Tour tour;
     double x;
     double y;
+    auto timeStart = std::chrono::high_resolution_clock::now();
     while (input >> x >> y) {
         Point p(x, y);
-        tour.insertNearest(p);
+        tour.insertSmallest(p);
         //uncomment the 4 lines below to animate
-        tour.draw(scene);
+        //tour.draw(scene);
-        std::chrono::milliseconds dura(50);
+        //std::chrono::milliseconds dura(50);
-        std::this_thread::sleep_for(dura);
+        //std::this_thread::sleep_for(dura);
-        a.processEvents();
+        //a.processEvents();
     }
     input.close();
+    auto took = std::chrono::high_resolution_clock::now() - timeStart;
 
     // print tour to standard output
     cout << "Tour distance: " << std::fixed << std::setprecision(4)
          << std::showpoint << tour.distance() << endl;
     cout << "Number of points: " << tour.size() << endl;
     tour.show();
+    cout << "Calculation took: " << took.count()*1E-6 << "ms" << endl;
 
     // draw tour
     tour.draw(scene);