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46 lines
1.1 KiB
46 lines
1.1 KiB
// Package triangle determines what kind of triangle three side lengths make.
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package triangle
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import "math"
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// An enumeration of triangle types
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const (
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NaT Kind = iota // Not a triangle
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Equ // Equlateral
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Iso // Isometric
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Sca // Scalene
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testVersion = 2
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)
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// A Kind is an integer representation of the kind of triangle.
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type Kind int
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// KindFromSides determines whether the three side lengths given
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// constitute a triangle and if so, what type of triangle it is.
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func KindFromSides(a, b, c float64) (k Kind) {
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// Return NaT when any side is zero, negative, infinite, or NaN.
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for _, f := range []float64{a, b, c} {
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if f <= 0 || f != f || math.IsInf(f, 0) {
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return NaT
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}
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}
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switch {
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// Return NaT if the sides fail triangle inequality tests.
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case a+b < c || b+c < a || a+c < b:
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k = NaT
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case a == b && b == c: // 3 equal length sides (Equ)
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k = Equ
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case a == b || b == c || a == c: // 2 equal length sides (Iso)
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k = Iso
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case a != b && b != c && a != c: // No equal length sides (Sca)
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k = Sca
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}
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return k
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}
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// Iteration 2 benkmark results:
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//
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// PASS
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// BenchmarkKind-12 2000000 651 ns/op
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//
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