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an example of beautiful ruby code used to validate a triangle as part of ruby koans exercise
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| # exercise is from http://rubykoans.com/ - a great way to learn ruby! | |
| #! my not so succinct but works solution | |
| def triangle(a, b, c) | |
| validate_triangle(a, b, c) | |
| if a == b && b == c | |
| :equilateral | |
| elsif a != b && b != c && c != a | |
| :scalene | |
| else | |
| :isosceles | |
| end | |
| end | |
| def validate_triangle(a, b, c) | |
| raise TriangleError, "No such thing as negative or 0-length sides in a triangle" if a <= 0 || b <= 0 || c <= 0 | |
| raise TriangleError, "Incomplete triangle because the sides cannot touch and close up" if a + b <= c || a + c <= b || b + c <= a | |
| end | |
| # === | |
| # Josh's beautiful solution taken from https://stackoverflow.com/a/14445542/6463816 | |
| # === | |
| def triangle(a, b, c) | |
| [a, b, c].permutation do |sides| | |
| raise TriangleError unless sides[0] + sides[1] > sides[2] | |
| end | |
| case [a,b,c].uniq.size | |
| when 3; :scalene | |
| when 2; :isosceles | |
| when 1; :equilateral | |
| end | |
| end | |
| class TriangleError < StandardError | |
| end |
Rather than sides[0] + sides[1] > sides[2], what about sides[0..1].sum > sides[2]?
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[].permutationis so easy to understand as a human! line 24[].uniq.sizeandwhen Nexpress the thing I'm trying to do in the form closest to how I think about it in my human mind. line 27