First iteration

triangle.go

@@ -1,17 +1,47 @@
 package triangle
 
-const testVersion = 2
+import "math"
 
-// Code this function.
-func KindFromSides(a, b, c float64) Kind
+const (
+	// An enumeration of triangle types
+	NaT Kind = iota
+	Equ
+	Iso
+	Sca
 
-// Notice it returns this type.  Pick something suitable.
-type Kind
+	testVersion = 2
+)
 
-// Pick values for the following identifiers used by the test program.
-NaT // not a triangle
-Equ // equilateral
-Iso // isosceles
-Sca // scalene
+// A Kind is an integer representation of the kind of triangle.
+type Kind int
 
-// Organize your code for readability.
+// KindFromSides determines whether the three side lengths given
+// constitute a triangle and if so, what type of triangle it is.
+func KindFromSides(a, b, c float64) Kind {
+	// Return NaT when any side is zero, negative, infinite, or NaN.
+	for _, f := range []float64{a, b, c} {
+		if f <= 0 || f != f || math.IsInf(f, 0) {
+			return NaT
+		}
+	}
+	// Return NaT if the sides fail triangle inequality tests.
+	if a+b < c || b+c < a || a+c < b {
+		return NaT
+	}
+	if a == b && b == c {
+		return Equ
+	}
+	if a == b || b == c || a == c {
+		return Iso
+	}
+	if a != b || b != c || a != c {
+		return Sca
+	}
+	return NaT
+}
+
+// Iteration 1 benkmark results:
+//
+// PASS
+// BenchmarkKind-12	 2000000	       643 ns/op
+// ok  	exercism/go/triangle	1.948s