Swift - 产生不重复的随机数

产生不重复的随机数

不考虑复杂度，简单粗暴法

struct Random {
   /**
    * 如区间表示 ==> [1, end]
    */
   static func number(end: Int) -> [Int] {
        var startArr = Array(1...end)
        var resultArr = Array(count: end, repeatedValue: 0)
        for i in 0..<startArr.count {
            let currentCount = UInt32(startArr.count - i)
            let index = Int(arc4random_uniform(currentCount))
            resultArr[i] = startArr[index]
            startArr[index] = startArr[Int(currentCount) - 1]
        }
        return resultArr
    }
    /**
     *  如半闭区间表示 ==> (start, end]
     */
    static func numberPro(start: Int, end: Int) -> [Int] {
        let scope = end - start
        var startArr = Array(1...scope)
        var resultArr = Array(count: scope, repeatedValue: 0)
        for i in 0..<startArr.count {
            let currentCount = UInt32(startArr.count - i)
            let index = Int(arc4random_uniform(currentCount))
            resultArr[i] = startArr[index]
            startArr[index] = startArr[Int(currentCount) - 1]
        }
        return resultArr.map { $0 + start }
    }
}

let A = Random.number(5)  
 // = [3, 2, 4, 5, 1]
let Apro = Random.numberPro(10, end: 20)
// = [16, 12, 17, 13, 18, 14, 15, 19, 11, 20]