Created
September 20, 2016 16:01
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| import Foundation | |
| #if os(Linux) | |
| import Glibc | |
| #endif | |
| struct Random { | |
| #if os(Linux) | |
| static var initialized = false | |
| #endif | |
| static func roll(max: Int) -> Int { | |
| #if os(Linux) | |
| if !Random.initialized { | |
| srandom(UInt32(time(nil))) | |
| Random.initialized = true | |
| } | |
| return Int(random() % max) | |
| #else | |
| return Int(arc4random_uniform(UInt32(max))) | |
| #endif | |
| } | |
| } | |
| extension Collection { | |
| func permutedIndices() -> [Indices.Iterator.Element] { | |
| typealias Index = Indices.Iterator.Element | |
| var remainingIndices: [Index] = Array(indices) | |
| var count = remainingIndices.count | |
| var results: [Index] = [] | |
| (0 ..< count).forEach { _ in | |
| defer { count -= 1 } | |
| let index = Random.roll(max: count) | |
| results.append(remainingIndices.remove(at: index)) | |
| } | |
| return results | |
| } | |
| } | |
| let test = ["a", "b", "c", "d"] | |
| for idx in test.permutedIndices() { | |
| print(test[idx]) | |
| } |
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