Data commit

Task/Heronian-triangles/Go/heronian-triangles.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+    "fmt"
+    "math"
+    "sort"
+)
+
+const (
+    n = 200
+    header = "\nSides          P   A"
+)
+
+func gcd(a, b int) int {
+    leftover := 1
+    var dividend, divisor int
+    if (a > b) { dividend, divisor = a, b } else { dividend, divisor = b, a }
+
+    for (leftover != 0) {
+        leftover = dividend % divisor
+        if (leftover > 0) {
+            dividend, divisor = divisor, leftover
+        }
+    }
+    return divisor
+}
+
+func is_heron(h float64) bool {
+    return h > 0 && math.Mod(h, 1) == 0.0
+}
+
+// by_area_perimeter implements sort.Interface for [][]int based on the area first and perimeter value
+type by_area_perimeter [][]int
+
+func (a by_area_perimeter) Len() int           { return len(a) }
+func (a by_area_perimeter) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a by_area_perimeter) Less(i, j int) bool {
+    return a[i][4] < a[j][4] || a[i][4] == a[j][4] && a[i][3] < a[j][3]
+}
+
+func main() {
+    var l [][]int
+    for c := 1; c <= n; c++ {
+        for b := 1; b <= c; b++ {
+            for a := 1; a <= b; a++ {
+                if (gcd(gcd(a, b), c) == 1) {
+                    p := a + b + c
+                    s := float64(p) / 2.0
+                    area := math.Sqrt(s * (s - float64(a)) * (s - float64(b)) * (s - float64(c)))
+                    if (is_heron(area)) {
+                        l = append(l, []int{a, b, c, p, int(area)})
+                    }
+                }
+            }
+        }
+    }
+
+    fmt.Printf("Number of primitive Heronian triangles with sides up to %d: %d", n, len(l))
+    sort.Sort(by_area_perimeter(l))
+    fmt.Printf("\n\nFirst ten when ordered by increasing area, then perimeter:" + header)
+    for i := 0; i < 10; i++ { fmt.Printf("\n%3d", l[i]) }
+
+    a := 210
+    fmt.Printf("\n\nArea = %d%s", a, header)
+    for _, it := range l  {
+        if (it[4] == a) {
+            fmt.Printf("\n%3d", it)
+        }
+    }
+}