added TSP (NN&2-opt) example

examples/TSP.cpp

+#include "cute.h"
+
+#include <algorithm>
+#include <vector>
+#include <cmath>
+using namespace cute;
+using namespace std;
+
+void nearestNeighbour();
+void twoOpt();
+
+
+void setup()
+{
+    registerAlgorithm(nearestNeighbour, "NearestNeighbour");
+    registerAlgorithm(twoOpt, "2-Opt :D");
+    setProblemSize(15);
+    setPlotTheme(3);
+    setPlotVisible((Plot)1, false);
+    setPlotVisible((Plot)2, false);
+    setPlotTitle((Plot)0, "Travelling Salesman Problem");
+}
+
+float length (const Point& a, const Point& b)
+{
+    return sqrt(pow((a.x - b.x), 2) + pow((a.y - b.y), 2));
+}
+
+namespace global
+{
+    vector<Point> result;
+
+} //namespace global
+
+
+void nearestNeighbour()
+{
+    resetPlot(0);
+    vector<Point>       input;
+    const vector<Point> points = getProblemData2D();
+    for (auto P : points)
+        input.push_back(P);
+
+    PlotProperties Pp;
+    Pp.color = Colors::darkRed;
+    Pp.onTop = true;
+    plotPoints(points, 0, Pp);
+    PlotProperties Lp;
+    Lp.color = Colors::green;
+
+    using global::result;
+    result.clear();
+    result.reserve(points.size());
+    result.push_back(input.front()); //start
+    Point currentPoint = input.front();
+    input.erase(input.begin());
+
+    int i = 1;
+    setProgress(100 * i / points.size());
+    setStatusMessage(to_string(i) + " of " + to_string(input.size()));
+
+    while (input.size() > 0)
+    {
+        ++i;
+        int  bestDist = INT_MAX;
+        auto bestIter = input.begin();
+
+        for (auto iter = input.begin(); iter != input.end(); ++iter)
+        {
+            float dist = length(currentPoint, *iter);
+            if (dist < bestDist)
+            {
+                bestDist = dist;
+                bestIter = iter;
+            }
+        }
+        currentPoint = *bestIter;
+        result.push_back(*bestIter);
+        input.erase(bestIter);
+        plotLines(result, 0, false, Lp);
+        delay(300);
+        undo(0);
+        setStatusMessage(to_string(i) + " of " + to_string(points.size()));
+        setProgress(100 * i / points.size());
+    }
+    Lp.color = Colors::cyan;
+    Lp.name  = "NN";
+    plotLines(result, 0, true, Lp);
+    setStatusMessage("DONE! :D");
+}
+
+void twoOpt()
+{
+    nearestNeighbour();
+    delay(1000);
+    using global::result;
+    result.emplace_back(result.front());
+    bool didSwap = true;
+    int  swaps   = 0;
+    setStatusMessage(to_string(swaps) + " swaps");
+    setProgress(0);
+    PlotProperties pp;
+    pp.color = Colors::darkCyan;
+    pp.size  = 12;
+    while (didSwap)
+    {
+        didSwap = false;
+        for (size_t i = 0; (i < (result.size() - 3)); ++i)
+        {
+            for (size_t j = i + 2; (j < (result.size() - 1)) & !didSwap; ++j)
+            {
+                auto a  = result[i];
+                auto b  = result[i + 1];
+                auto c  = result[j];
+                auto d  = result[j + 1];
+                auto ab = length(a, b);
+                auto cd = length(c, d);
+                auto ac = length(a, c);
+                auto bd = length(b, d);
+
+                if (ac + bd < ab + cd)
+                {
+                    reverse(result.begin() + i + 1,
+                            result.begin() + j + 1); //needs j+1 otherwise doesnt include last element
+                    didSwap = true;
+                    ++swaps;
+                    plotLines(result, 0, false, pp);
+                    delay(500);
+                    undo(0);
+                    setStatusMessage(to_string(swaps) + " swaps");
+                }
+            }
+        }
+    }
+    pp.color = Colors::magenta;
+    pp.color.transparency = 3 * 255 / 4;
+    pp.size               = pp.size * 2;
+    pp.name               = "2-Opt";
+    plotLines(result, 0, false, pp);
+    setStatusMessage("DONE! :DD");
+    setProgress(100);
+}