From 7b7f6808a7b2db2ed21103767434c1445f7815c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustav=20S=C3=B6rn=C3=A4s?= <gustav@sornas.net>
Date: Thu, 3 Dec 2020 16:27:06 +0100
Subject: add given files l7

---
 labb7/src/brute.cpp | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 labb7/src/brute.cpp

(limited to 'labb7/src/brute.cpp')

diff --git a/labb7/src/brute.cpp b/labb7/src/brute.cpp
new file mode 100644
index 0000000..ffddd0f
--- /dev/null
+++ b/labb7/src/brute.cpp
@@ -0,0 +1,94 @@
+/*
+ * TDDD86 Pattern Recognition
+ * This program computes and plots all line segments involving 4 points
+ * in a file using Qt.
+ */
+
+#include <QApplication>
+#include <QGraphicsView>
+#include <QGraphicsScene>
+#include <fstream>
+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <chrono>
+#include "Point.h"
+
+// constants
+static const int SCENE_WIDTH = 512;
+static const int SCENE_HEIGHT = 512;
+
+void render_points(QGraphicsScene* scene, const vector<Point>& points) {
+    for(const auto& point : points) {
+        point.draw(scene);
+    }
+}
+
+void render_line(QGraphicsScene* scene, const Point& p1, const Point& p2) {
+    p1.lineTo(scene, p2);
+}
+
+int main(int argc, char *argv[]) {
+    QApplication a(argc, argv);
+
+    // open file
+    string filename = "input100.txt";
+    ifstream input;
+    input.open(filename);
+
+    // the vector of points
+    vector<Point> points;
+
+    // read points from file
+    int N;
+    int x;
+    int y;
+
+    input >> N;
+
+    for (int i = 0; i < N; ++i) {
+        input >> x >> y;
+        points.push_back(Point(x, y));
+    }
+    input.close();
+
+    // setup graphical window
+    QGraphicsView *view = new QGraphicsView();
+    QGraphicsScene *scene = new QGraphicsScene(0, 0, SCENE_WIDTH, SCENE_HEIGHT);
+    view->setScene(scene);
+    // draw points to screen all at once
+    render_points(scene, points);
+    view->scale(1, -1); //screen y-axis is inverted
+    view->resize(view->sizeHint());
+    view->setWindowTitle("Brute Force Pattern Recognition");
+    view->show();
+
+    // sort points by natural order
+    // makes finding endpoints of line segments easy
+    sort(points.begin(), points.end());
+    auto begin = chrono::high_resolution_clock::now();
+
+    // iterate through all combinations of 4 points
+    for (int i = 0 ; i < N-3 ; ++i) {
+        for (int j = i+1 ; j < N-2 ; ++j) {
+            for (int k = j+1 ; k < N-1 ; ++k) {
+                //only consider fourth point if first three are collinear
+                if (points.at(i).slopeTo(points.at(j)) == points.at(i).slopeTo(points.at(k))) {
+                    for (int m{k+1} ; m < N ; ++m) {
+                        if (points.at(i).slopeTo(points.at(j)) == points.at(i).slopeTo(points.at(m))) {
+                            render_line(scene, points.at(i), points.at(m));
+                            a.processEvents(); // show rendered line
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    auto end = chrono::high_resolution_clock::now();
+    cout << "Computing line segments took "
+         << std::chrono::duration_cast<chrono::milliseconds>(end - begin).count()
+         << " milliseconds." << endl;
+
+    return a.exec(); // start Qt event loop
+}
-- 
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