recurrence 递归算法

//求阶乘
import UIKit

func multi(A:Int) -> Int{
    //let n = A
    if A == 0{
        return 1
    } else {
        return multi(A-1)*A
    }
}
var ans = multi(3)

//汉诺塔
import UIKit
func hanoi(a:String,b:String,c:String,n:Int){
    
    if n == 1{
        print("move the \(n) disk from \(a) to \(c)")
    }else{
        hanoi(a,b:c,c:b,n:n-1)
        print("move the \(n) disk from \(a) to \(c)")
        hanoi(b,b:a,c:c,n:n-1)
        
    }
}
hanoi("A",b:"B",c:"C",n:4)

import UIKit
//受限汉诺塔
func hanoi(a:String,b:String,c:String,n:Int){
    
    if n == 1{
        print("move the \(n) disk from \(a) to \(b)")
        print("move the \(n) disk from \(b) to \(c)")
    }else{
        hanoi(a,b:b,c:c,n:n-1)
        print("move the \(n) disk from \(a) to \(b)")
        hanoi(c,b:b,c:a,n:n-1)
        print("move the \(n) disk from \(b) to \(c)")
        hanoi(a,b:b,c:c,n:n-1)
        
    }
}
hanoi("A",b:"B",c:"C",n:3)

//找到一个数组的最小值 用递归的方法
func Riddle(A:[Int]) -> Int{
    var array = A       //必须将A赋值给array，因为默认A为常量，不能进行删除操作
    if array.count == 1{
        return array[0]
    }else{
        let last = array.removeLast()
        let temp = Riddle(array)
        if temp <= last {
            return temp
        }else{
            return last
        }
    }
}
let n = Riddle([1,2,3,5,0,7])