Initial data commit

Task/Heronian-triangles/Java/heronian-triangles.java

@@ -0,0 +1,77 @@
+import java.util.ArrayList;
+
+public class Heron {
+    public static void main(String[] args) {
+        ArrayList<int[]> list = new ArrayList<>();
+
+        for (int c = 1; c <= 200; c++) {
+            for (int b = 1; b <= c; b++) {
+                for (int a = 1; a <= b; a++) {
+
+                    if (gcd(gcd(a, b), c) == 1 && isHeron(heronArea(a, b, c))){
+                        int area = (int) heronArea(a, b, c);
+                        list.add(new int[]{a, b, c, a + b + c, area});
+                    }
+                }
+            }
+        }
+        sort(list);
+
+        System.out.printf("Number of primitive Heronian triangles with sides up "
+                + "to 200: %d\n\nFirst ten when ordered by increasing area, then"
+                + " perimeter:\nSides       Perimeter   Area", list.size());
+
+        for (int i = 0; i < 10; i++) {
+            System.out.printf("\n%d x %d x %d   %d      %d",
+                    list.get(i)[0], list.get(i)[1], list.get(i)[2],
+                    list.get(i)[3], list.get(i)[4]);
+        }
+
+        System.out.printf("\n\nArea = 210\nSides        Perimeter   Area");
+        for (int i = 0; i < list.size(); i++) {
+            if (list.get(i)[4] == 210)
+                System.out.printf("\n%d x %d x %d   %d      %d",
+                        list.get(i)[0], list.get(i)[1], list.get(i)[2],
+                        list.get(i)[3], list.get(i)[4]);
+        }
+    }
+
+    public static double heronArea(int a, int b, int c) {
+        double s = (a + b + c) / 2f;
+        return Math.sqrt(s * (s - a) * (s - b) * (s - c));
+    }
+
+    public static boolean isHeron(double h) {
+        return h % 1 == 0 && h > 0;
+    }
+
+    public static int gcd(int a, int b) {
+        int leftover = 1, dividend = a > b ? a : b, divisor = a > b ? b : a;
+        while (leftover != 0) {
+            leftover = dividend % divisor;
+            if (leftover > 0) {
+                dividend = divisor;
+                divisor = leftover;
+            }
+        }
+        return divisor;
+    }
+
+    public static void sort(ArrayList<int[]> list) {
+        boolean swapped = true;
+        int[] temp;
+        while (swapped) {
+            swapped = false;
+            for (int i = 1; i < list.size(); i++) {
+                if (list.get(i)[4] < list.get(i - 1)[4] ||
+                        list.get(i)[4] == list.get(i - 1)[4] &&
+                        list.get(i)[3] < list.get(i - 1)[3]) {
+                    temp = list.get(i);
+                    list.set(i, list.get(i - 1));
+                    list.set(i - 1, temp);
+                    swapped = true;
+                }
+            }
+        }
+    }
+}