comments and structure improvements

inf2440/hw4/Oblig4.java

@@ -3,13 +3,9 @@ abstract class Oblig4 {
 	int x[];
 	int y[];
 	int n;
-	int MAX_Y;
 	int MAX_X;
+	int MAX_Y;
 
-	int minX;
-	int maxX;
-	int minY;
-	int maxY;
 	IntList coHull;
 	NPunkter17 points;
 	String name = "Oblig4";
@@ -23,13 +19,25 @@ abstract class Oblig4 {
 		points.fyllArrayer(x, y);
 	}
 
+	// This method should be overwritten by each implementation.
+	// It's responsible for filling in MAX_X, MAX_Y, and coHull
 	abstract void solve();
 
+	/*
+	 * The rest is utility methods which any implementation will use.
+	 */
+
+	// Draw points using TegnUt.
+	// Requires x, y, n, MAX_X, MAX_Y, and coHull
+	// to be filled out.
 	void draw() {
 		TegnUt t = new TegnUt(this, coHull, name);
 		t.setVisible(true);
 	}
 
+	// a, b, and c will be used in the line equation.
+	// It doesn't make sense to recalculate them all the time,
+	// as they only depend on p1 and p2.
 	int lineA(int p1, int p2) {
 		return y[p1] - y[p2];
 	}
@@ -62,4 +70,56 @@ abstract class Oblig4 {
 	double dist(double l, int a, int b) {
 		return l / Math.sqrt((a * a) + (b * b));
 	}
+
+	// Create a list of points, in sorted order, on the line
+	// given by (a, b, c, p1)
+	IntList addPointsOnLine(IntList indexes, int a, int b, int c, int p1) {
+		IntList l = new IntList();
+
+		// Add points on the line between p1 and p2
+		for (int i = 0; i < indexes.size(); ++i) {
+			int idx = indexes.get(i);
+
+			double line = lineEquation(a, b, c, idx);
+			if (line == 0)
+				l.add(idx);
+		}
+
+		// Calculate distances for sorting
+		double[] dists = new double[l.size()];
+		for (int i = 0; i < l.size(); ++i) {
+			dists[i] = pointDist(p1, l.get(i));
+		}
+
+		// Sort points based on distance from p1
+		// (Bubble sort, but it's usually really few elements)
+		boolean sorted;
+		do {
+			sorted = true;
+
+			// Loop through points, swap non-sorted ones
+			for (int i = 1; i < l.size(); ++i) {
+				double dist = dists[i];
+				double prevDist = dists[i - 1];
+
+				// Skip if already sorted
+				if (prevDist <= dist)
+					continue;
+
+				sorted = false;
+
+				// Swap indexes
+				int tmpi = l.data[i];
+				l.data[i] = l.data[i - 1];
+				l.data[i - 1] = tmpi;
+
+				// Swap distances
+				double tmpd = dists[i];
+				dists[i] = dists[i - 1];
+				dists[i - 1] = tmpd;
+			}
+		} while (!sorted);
+
+		return l;
+	}
 }

inf2440/hw4/Sequential.java

@@ -1,4 +1,5 @@
 class Sequential extends Oblig4 {
+
 	Sequential(NPunkter17 points) {
 		super(points);
 		name = "Sequential";
@@ -6,16 +7,16 @@ class Sequential extends Oblig4 {
 
 	@Override
 	void solve() {
-		findMinMaxXY();
-		MAX_X = x[maxX];
-		MAX_Y = y[maxY];
+		MinMaxXY minmax = findMinMax();
+		MAX_X = x[minmax.maxX];
+		MAX_Y = y[minmax.maxY];
 
 		IntList indexes = new IntList(n);
 		for (int i = 0; i < n; ++i)
 			indexes.add(i);
 
-		coHull = pointsRightOf(maxX, minX, indexes);
-		coHull.append(pointsRightOf(minX, maxX, indexes));
+		coHull = pointsRightOf(minmax.maxX, minmax.minX, indexes);
+		coHull.append(pointsRightOf(minmax.minX, minmax.maxX, indexes));
 
 		for (int i = 0; i < coHull.size(); ++i) {
 			System.out.print(coHull.get(i)+" ");
@@ -23,11 +24,15 @@ class Sequential extends Oblig4 {
 		System.out.println("");
 	}
 
-	void findMinMaxXY() {
-		minX = 0;
-		maxX = 0;
-		minY = 0;
-		maxY = 0;
+	class MinMaxXY {
+		int minX, maxX, maxY;
+	}
+
+	MinMaxXY findMinMax() {
+		int minX = 0;
+		int maxX = 0;
+
+		int maxY = 0;
 
 		for (int i = 1; i < n; ++i) {
 			int px = x[i];
@@ -37,61 +42,15 @@ class Sequential extends Oblig4 {
 				maxX = i;
 
 			int py = y[i];
-			if (py < y[minY])
-				minY = i;
 			if (py > y[maxY])
 				maxY = i;
 		}
-	}
-
-	IntList addPointsOnLine(IntList indexes, int a, int b, int c, int p1) {
-		IntList l = new IntList();
-
-		// Add points on the line between p1 and p2
-		for (int i = 0; i < indexes.size(); ++i) {
-			int idx = indexes.get(i);
-
-			double line = lineEquation(a, b, c, idx);
-			if (line == 0)
-				l.add(idx);
-		}
-
-		// Calculate distances for sorting
-		double[] dists = new double[l.size()];
-		for (int i = 0; i < l.size(); ++i) {
-			dists[i] = pointDist(p1, l.get(i));
-		}
-
-		// Sort points based on distance from p1
-		// (Bubble sort, but it's usually really few elements)
-		boolean sorted;
-		do {
-			sorted = true;
-
-			// Loop through points, swap non-sorted ones
-			for (int i = 1; i < l.size(); ++i) {
-				double dist = dists[i];
-				double prevDist = dists[i - 1];
-
-				// Skip if already sorted
-				if (prevDist <= dist)
-					continue;
 
-				sorted = false;
-
-				// Swap indexes
-				int tmpi = l.data[i];
-				l.data[i] = l.data[i - 1];
-				l.data[i - 1] = tmpi;
-
-				// Swap distances
-				double tmpd = dists[i];
-				dists[i] = dists[i - 1];
-				dists[i - 1] = tmpd;
-			}
-		} while (!sorted);
-
-		return l;
+		MinMaxXY minmax = new MinMaxXY();
+		minmax.minX = minX;
+		minmax.maxX = maxX;
+		minmax.maxY = maxY;
+		return minmax;
 	}
 
 	IntList pointsRightOf(int p1, int p2, IntList indexes) {