10元最多可喝多少瓶啤酒？（不可借酒+可借酒，swift语言实现）

酒吧不可以借酒

酒吧可以借酒

//
//  main.swift
//  beerMaxDrink
//
//  Created by on 2020/2/4.
//  Copyright © 2020. All rights reserved.
//
/*
 酒吧啤酒2元一瓶，两个空瓶或四个瓶盖可以换一瓶啤酒（酒吧概不借酒），你有10元钱，请问最多可以喝几瓶？
 */

import Foundation

//共累计喝的瓶数
var drinkSum = 0
//当前瓶子数
var bottleNum = 0
//当前瓶盖数
var capsNum = 0

//返回（累计喝瓶数，剩余瓶子数，剩余瓶盖数）
func getMaxDrinkSum(money:Float,price:Float) ->(Int,Int,Int) {

    bottleNum = Int(money / price)
    capsNum = bottleNum
    drinkSum = bottleNum
    
    //开始换酒,是个循环
    while bottleNum > 1 || capsNum > 3 {
        //酒瓶换
        let wineAddedByBottle = bottleNum / 2
        drinkSum += wineAddedByBottle
        bottleNum = bottleNum % 2 + wineAddedByBottle
        capsNum += wineAddedByBottle
        
        //酒盖换
        let wineAddedByCaps = capsNum / 4
        drinkSum += wineAddedByCaps
        capsNum = capsNum % 4 + wineAddedByCaps
        bottleNum += wineAddedByCaps
    }
    return (drinkSum,bottleNum,capsNum)
}

//可以借酒时，返回（累计喝瓶数，剩余瓶子数，剩余瓶盖数）
func getMaxDrinkSumCanBorrow(money:Float,Int) {

    var borrowedNum = 0
    bottleNum = Int(money / price)
    capsNum = bottleNum
    drinkSum = bottleNum
    
    //开始换酒,是个循环
    while bottleNum >= 1 || capsNum >= 3 {
 
        //酒瓶换
        let wineAddedByBottle = bottleNum / 2
        drinkSum += wineAddedByBottle
        bottleNum = bottleNum % 2 + wineAddedByBottle
        capsNum += wineAddedByBottle
        
        //如果（2酒瓶2酒盖时，"酒瓶换"已经把2酒瓶换为1瓶1盖，即变为1瓶3盖）借一瓶后，空瓶和瓶盖能换的酒数 <= 已借瓶数时，结束;否则，借一瓶
        if 1 == bottleNum || 3 == capsNum{//不能少，否则在循环时会提前借酒
            if (bottleNum + 1)/2 + (capsNum + 1)/4 <= borrowedNum {
                
                //不应该喝一瓶，回退
                bottleNum += 1
                capsNum -= 1
                return (drinkSum - 1,bottleNum - borrowedNum,capsNum - borrowedNum)
            }else{ //借一瓶
                borrowedNum += 1
                bottleNum += 1
                capsNum += 1
                
                //酒瓶换
                let wineAddedByBottle = bottleNum / 2
                drinkSum += wineAddedByBottle
                bottleNum = bottleNum % 2 + wineAddedByBottle
                capsNum += wineAddedByBottle
            }
        }
        
        //酒盖换
        let wineAddedByCaps = capsNum / 4
        drinkSum += wineAddedByCaps
        capsNum = capsNum % 4 + wineAddedByCaps
        bottleNum += wineAddedByCaps
    }
    return (drinkSum,capsNum)
}

for i in 0..<20{
    let rslt0 = getMaxDrinkSum(money: Float(i),price: 2)
    print("-----------------------")
    print("\(i)元：不能借酒：\(rslt0)")

    let rsltCanBorrow0 = getMaxDrinkSumCanBorrow(money: Float(i),price: 2)
    print("能借酒：\(rsltCanBorrow0)")
}

let rslt1 = getMaxDrinkSum(money: 10.0,price: 5)

print("-----------------------")
print("酒价格5元时，不能借酒：\(rslt1)")

let rsltCanBorrow1 = getMaxDrinkSumCanBorrow(money: 10.0,price: 5)
print("能借酒：\(rsltCanBorrow1)")

-----------------------
0元：不能借酒：(0,0)
能借酒：(0,0)
-----------------------
1元：不能借酒：(0,0)
-----------------------
2元：不能借酒：(1,1,1)
能借酒：(4,0)
-----------------------
3元：不能借酒：(1,0)
-----------------------
4元：不能借酒：(3,3)
能借酒：(8,0)
-----------------------
5元：不能借酒：(3,0)
-----------------------
6元：不能借酒：(7,3)
能借酒：(12,0)
-----------------------
7元：不能借酒：(7,0)
-----------------------
8元：不能借酒：(11,3)
能借酒：(16,0)
-----------------------
9元：不能借酒：(11,0)
-----------------------
10元：不能借酒：(15,3)
能借酒：(20,0)
-----------------------
11元：不能借酒：(15,0)
-----------------------
12元：不能借酒：(19,3)
能借酒：(24,0)
-----------------------
13元：不能借酒：(19,0)
-----------------------
14元：不能借酒：(23,3)
能借酒：(28,0)
-----------------------
15元：不能借酒：(23,0)
-----------------------
16元：不能借酒：(27,3)
能借酒：(32,0)
-----------------------
17元：不能借酒：(27,0)
-----------------------
18元：不能借酒：(31,3)
能借酒：(36,0)
-----------------------
19元：不能借酒：(31,0)
-----------------------
酒价格5元时，不能借酒：(3,0)
Program ended with exit code: 0