Created
August 13, 2015 23:18
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| import UIKit | |
| class Fraction { | |
| var n: Int | |
| var d: Int | |
| init(numerator: Int, denominator:Int) { | |
| self.n = numerator | |
| self.d = denominator | |
| } | |
| var description: String { | |
| if isImproper { | |
| return mixedPart > 0 ? "\(wholePart) \(mixedPart)/\(d)" : "\(wholePart)" | |
| } | |
| return d == 1 ? "\(n)" : "\(n)/\(d)" | |
| } | |
| var value: Double { | |
| get { return Double(n) / Double(d) } | |
| } | |
| var isImproper: Bool { | |
| get { return n >= d } | |
| } | |
| var wholePart: Int { | |
| get { return n / d } | |
| } | |
| var mixedPart: Int { | |
| get { return n % d } | |
| } | |
| } | |
| // 最大公約数 | |
| func greatestCommonDenominator(first: Int, second: Int) -> Int { | |
| return second == 0 ? first : greatestCommonDenominator(second, first % second) | |
| } | |
| func * (left: Fraction, right: Fraction) -> Fraction { | |
| var n = left.n * right.n | |
| var d = left.d * right.d | |
| let g = greatestCommonDenominator(n, d) | |
| n /= g | |
| d /= g | |
| return Fraction(numerator: n, denominator: d) | |
| } | |
| func * (left: Int, right: Fraction) -> Fraction { | |
| return Fraction(numerator: left, denominator: 1) * right | |
| } | |
| func * (left: Fraction, right: Int) -> Fraction { | |
| return left * Fraction(numerator: right, denominator: 1) | |
| } | |
| func / (left: Fraction, right: Fraction) -> Fraction { | |
| var n = left.n * right.d | |
| var d = left.d * right.n | |
| let g = greatestCommonDenominator(n, d) | |
| n /= g | |
| d /= g | |
| return Fraction(numerator: n, denominator: d) | |
| } | |
| func / (left: Int, right: Fraction) -> Fraction { | |
| return Fraction(numerator: left, denominator: 1) / right | |
| } | |
| func / (left: Fraction, right: Int) -> Fraction { | |
| return left / Fraction(numerator: right, denominator: 1) | |
| } | |
| func + (left: Fraction, right: Fraction) -> Fraction { | |
| var n = left.n * right.d + right.n * left.d | |
| var d = left.d * right.d | |
| let g = greatestCommonDenominator(n, d) | |
| n /= g | |
| d /= g | |
| return Fraction(numerator: n, denominator: d) | |
| } | |
| func + (left: Int, right: Fraction) -> Fraction { | |
| return Fraction(numerator: left, denominator: 1) + right | |
| } | |
| func + (left: Fraction, right: Int) -> Fraction { | |
| return left + Fraction(numerator: right, denominator: 1) | |
| } | |
| func - (left: Fraction, right: Fraction) -> Fraction { | |
| var n = left.n * right.d - right.n * left.d | |
| var d = left.d * right.d | |
| let g = greatestCommonDenominator(n, d) | |
| n /= g | |
| d /= g | |
| return Fraction(numerator: n, denominator: d) | |
| } | |
| func - (left: Int, right: Fraction) -> Fraction { | |
| return Fraction(numerator: left, denominator: 1) - right | |
| } | |
| func - (left: Fraction, right: Int) -> Fraction { | |
| return left - Fraction(numerator: right, denominator: 1) | |
| } |
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@takatoshi Thanks for your class! I've added init by String. It helps in real life usage.
https://gist.github.com/lanserxt/2d08ca8de2ca8f416973741a0cce498a