import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

   //        paixu()
   //        daoxu()
   //        shaixuan()
   //        xunzao()
   //        erfenfa()
   //        print(digui())
   //        sushu()
    gongyueshu(a: 55, b: 100)
}

/**  氣泡排序  */
func paixu() {
    var arr = [24,17,85,13,9,54,76,45,5,63]
    for i in 0..<arr.count {
        for j in 0..<arr.count - 1 - i {
            if arr[j] < arr[j + 1] {
                let tmp = arr[j]
                arr[j] = arr[j+1]
                arr[j+1] = tmp
            }
        }
    }
    print(arr)
    //sort 是對陣列本身進行排序，也就是意味著 sort 方法會修改陣列本身的內容。 而 sorted 就不會修改原有的陣列，而是返回一個經過排序處理後的新的陣列
    arr.sort {$0 < $1}
    print(arr)
    print(arr.sorted {$0 < $1})
}
/**  倒序輸出  */
func daoxu() {
    let str = "how are you"
    //先拆分成陣列
    let arr = str.characters.split(separator: " ").map(String.init)
    //倒序輸出
    //reversed 方法可以將陣列中的元素倒序排列
    let arr1 = Array(arr.reversed())
    print(arr1)
    for item in arr1 {
        print(item)
    }
}
/**  篩選  */
func shaixuan() {
    let arr = [2,3,4,5,4,3,7,8,3]
    //用集合最簡單
    let set = Set(arr)
    let arr1 = Array(set)

    print(arr1)
    //字典篩選key
    var dic = Dictionary<Int, Any>()
    for item in arr {
        dic[item] = item
    }
    print(Array(dic.keys))
}
/**  給定一個字串，輸出本字串中只出現一次並且最靠前的那個字元的位置？如“abaccddeeef”,字元是b,輸出應該是2  */
func xunzao() {
    let str = "abaccddeeef"
    var arr = Array<Character>()
    var arr1 = Array<Character>()
    for item in str.characters {
        if arr.contains(item) {
            arr1.append(item)
        }else{
            arr.append(item)
        }
    }
    var arr2 = Array<Character>()
    var arr3 = Array<Character>()
    for item in str.characters {
        if !arr1.contains(item) {
            arr2.append(item)
        }
        arr3.append(item)
    }
    print(arr3.index(of: arr2.first!)! + 1)

}
/**  二分法查詢（只實用於有序陣列）  */
func erfenfa() {//36
    let tmp = 36

    var array = [1, 2, 50, 3, 9, 5, 5, 7, 10, 36]
    //先排序
    array.sort()
    print(array)
    var left = 0
    var right = (array.count - 1)

    while left <= right {
        let mid = (left + right) / 2
        let value = array[mid]
        if value == tmp {
            return
        }
        if value < tmp {
            left = mid + 1
        }
        if value > tmp {
            right = mid - 1
        }
    }
}
/**  遞迴法查詢  */
var left = 0
func digui() -> Int {
    let tmp = 36

    var array = [1, 2, 50, 3, 9, 5, 5, 7, 10, 36]
    let right = (array.count - 1)
    var mid = (left + right) / 2
    let value = array[mid]

    if left > right {
        return -1
    }else{
        left += 1
        if value == tmp {
            return mid
        }else if value > tmp {
            mid = mid - 1
            return self.digui()
        }else{
            mid = mid + 1
            return self.digui()
        }
    }
}

/**  2-100之間的素數  */
func sushu() {
    for i in 2..<100 {
        var r : Int = 1
        for j in 2..<i {
            if i%j == 0 {
                r = 0
                break
            }
        }
        if r == 1 {
            print(i)
        }
    }
}
/**  兩個整數的最大公約數  */
func gongyueshu( a:Int, b:Int) {
    var a = a
    var b = b
    var tmp = 0
    if a < b {
        tmp = a
        a = b
        b = tmp
    }
    while b != 0 {
        tmp = a%b
        a = b
        b = tmp
    }
    print(a)
}






override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
 

}

希望能幫到大家！