根据总用量计算每种包装规格的购买量和总价后续篇（一）并且使得用户花费最少

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　　在根据总用量计算每种包装规格的购买量和总价中讲述了一个开发的场景，首先有一个总共的土地拥有量：total亩，现在有n种可以选择的商品，每一种商品都有每亩的用量：amount/亩，每一种商品都有多个包装规格，每个包装规格有自己的包装量和售价。

　　需求就是计算出，在给定土地上面种植那种商品需要的花费最少，也就是可以用最少的钱来买更多的东西种地，满足我种地的最大需求量。

　　其实我们还假设了一个前提，就是包装大的单价低，好比100克每包的可能买100元，200克每包的就应该卖180元，肯定会小于两个100克每包的价格，这个也是市场调研的结果，也比较符合市场常规。

　　代码中用到了二分搜索法的思路，其实我需要的是一个定位，定位我需要购买的最合算的包装规格，也就是在满足需要的情况下，尽可能购买大包装。

　　例如：现在有两个商品，土豆和白菜，土豆有三个规格，100克每包的100元，200克每包的180元，300克每包的240元；白菜有四个规格，100克每包的70元，200克每包的130元，300克每包的200元，400克每包的300元。种白菜每亩要100斤，中土豆每亩尧200斤。我总共有1029亩地，计算一下，是种土豆花费少？还是种白菜花费少？

　　有两个点要注意：1）找位置，找到我需要购买的最合算的包装规格的位置，使用了二分搜索2）计算用量和预算。

　　计算一种商品最少花费的伪代码如下：

　　输入：一个商品的信息，包括包装规格

　　输出:需要购买的包装规格几个数，总共的花费

　　计算过程：

　　{

　　　　while（总量>最小包装规格的量）

　　　　{

　　　　　　1）找位置，定位包装规格

　　　　　　2）计算需要购买多少个第一步找到的包装规格

　　　　　　3）需要购买的个数=总量和包装规格的包装量取整

　　　　　　4）总量=总量-需要购买的个数*包装规格的包装量

　　　　　　5）这种商品的预算+=需要购买的个数*包装规格的单价

　　　　}

　　　　if（总量<=最小包装规格的量）

　　　　{

　　　　　　说明零头就只能买个最小包装了，因为购买不支持散买。

　　　　}

　　示例代码下载：/Files/virusswb/BeautyCode.ConApp.rar

　　代码如下：

代码

/*
* Created by SharpDevelop.
* User: haier
* Date: 2010-3-23
* Time: 22:19
*
* To change this template use Tools | Options | Coding | Edit Standard Headers.
*/
using System;
using System.Collections.Generic;

namespace BeautyCode.ConApp
{
    /// <summary>
    /// 种植方案
    /// </summary>
    public class PlantArea
    {
        /// <summary>
        /// 种植面积,单位是亩
        /// </summary>
        public static decimal PlantAreaAmount=175.25m;
    }
    /// <summary>
    /// 商品类型
    /// </summary>
    public enum ProductType
    {
        /// <summary>
        /// 种子
        /// </summary>
        Seed,
        /// <summary>
        /// 肥料
        /// </summary>
        Fertilizer,
        /// <summary>
        /// 农药
        /// </summary>
        Pesticide
    }

    public enum FertType
    {
        /// <summary>
        /// 底肥
        /// </summary>
        DiF,
        /// <summary>
        /// 种肥
        /// </summary>
        ZhongF,
        /// <summary>
        /// 追肥
        /// </summary>
        ZhuiF
    }
    public class Unit
    {
        public Guid ID{set;get;}

        public string CnName{set;get;}
    }
    public class PkgPrice
    {
        public Guid PkgID{set;get;}
        /// <summary>
        /// 包装量
        /// </summary>
        public decimal PkgAmount{set;get;}
        /// <summary>
        /// 包装单位
        /// </summary>
        public Unit PkgUnit{set;get;}
        /// <summary>
        /// 包装价格
        /// </summary>
        public decimal Price{set;get;}
        /// <summary>
        /// 选中的包装个数
        /// </summary>
        public int Quantities{set;get;}
    }

    public class Product
    {
        public virtual Guid ID{set;get;}
        public virtual string Name{set;get;}
        public virtual ProductType ProType{set;get;}
        /// <summary>
        /// 每亩用量
        /// </summary>
        public virtual decimal Amount{set;get;}
        /// <summary>
        /// 每亩用量单位
        /// </summary>
        public virtual Unit ProductUnit{set;get;}
        /// <summary>
        /// 总用量
        /// </summary>
        public virtual decimal TotalAmount{set;get;}
        public Product (ProductType type)
        {
            this.ProType=type;
        }
        /// <summary>
        /// 预算
        /// </summary>
        public decimal Budget{set;get;}
        /// <summary>
        /// 全部包装类型
        /// </summary>
        public List<PkgPrice > AllPkgPrice{set;get;}
        /// <summary>
        /// 选中的包装类型
        /// </summary>
        public List<PkgPrice > SelectPkgPrice{set;get;}
    }
    public class Seed:Product
    {
        public Seed ():base(ProductType.Seed ){}

        public List<Pesticide > Pesticides{set;get;}
        public List<DiF > DiFs{set;get;}
        public List<ZhongF >ZhongFs{set;get;}
        public List<ZhuiF >ZhuiFs{set;get;}
    }
    public class Fertilizer:Product
    {public FertType FType{set;get;}
        public Fertilizer (FertType type):base (ProductType.Fertilizer){
        this.FType=type ;
        }
    }
    public class DiF:Fertilizer
    {
        public DiF ():base (FertType.DiF ){}
    }
    public class ZhongF:Fertilizer
    {
        public ZhongF ():base (FertType .ZhongF ){}
    }
    public class ZhuiF:Fertilizer
    {
        public ZhuiF ():base (FertType.ZhuiF ){}
    }
    public class Pesticide:Product
    {
        public Pesticide ():base(ProductType.Pesticide ){}
    }
    /// <summary>
    /// Description of BeiBao.
    /// </summary>
    public class BeiBao
    {
        public List<Seed  >Seeds=null;
        public Seed  Seed=null;
        public List<Pesticide >Pesticides=null;
        public Pesticide Pesticide=null;
        public List<DiF >DiFs=null;
        public DiF DiF=null;
        public List<ZhongF >ZhongFs=null;
        public ZhongF ZhongF=null;
        public List<ZhuiF >ZhuiFs=null;
        public ZhuiF ZhuiF=null;
        public List<PkgPrice > PkgPrices=null;
        public BeiBao()
        {
            Seeds =new List<Seed  >();
            Seed =new Seed(){ ID=Guid.NewGuid (),
                Name="土豆", Amount =120, Budget=0,
                TotalAmount =120*PlantArea.PlantAreaAmount };
            PkgPrices =new List<PkgPrice>(){
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =100, Price=23},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =210, Price=58},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =130, Price=39}};
            Seed .AllPkgPrice =PkgPrices ;
            Seed.AllPkgPrice.Sort(new Comparison<PkgPrice >(comparePkgAmountAsc));
            Seeds.Add(Seed );
            Seed =new Seed(){ ID=Guid.NewGuid (),
                Name="白菜", Amount =150, Budget=0, TotalAmount =150*PlantArea.PlantAreaAmount };
            PkgPrices =new List<PkgPrice>(){
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =80, Price=20},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =180, Price=48},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =110, Price=34}};
            Seed .AllPkgPrice =PkgPrices ;
                Seed.AllPkgPrice.Sort(new Comparison<PkgPrice >(comparePkgAmountAsc));
            Seeds.Add(Seed );
            Seed =new Seed(){ ID=Guid.NewGuid (),
                Name="萝卜", Amount =100, Budget=0, TotalAmount =100*PlantArea.PlantAreaAmount };
            PkgPrices =new List<PkgPrice>(){
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =110, Price=35},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =250, Price=79},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =170, Price=49}};
            Seed .AllPkgPrice =PkgPrices ;
                Seed.AllPkgPrice.Sort(new Comparison<PkgPrice >(comparePkgAmountAsc));
            Seeds.Add(Seed );
            Seed =new Seed(){ ID=Guid.NewGuid (),
                Name="大豆", Amount =20, Budget=0, TotalAmount =20*PlantArea.PlantAreaAmount };
            PkgPrices =new List<PkgPrice>(){
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =110, Price=35},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =250, Price=79},
                new PkgPrice (){ PkgID=Guid.NewGuid (),PkgAmount =170, Price=49}};
            Seed .AllPkgPrice =PkgPrices ;
                Seed.AllPkgPrice.Sort(new Comparison<PkgPrice >(comparePkgAmountAsc));
            Seeds.Add(Seed );
        }

        public Product ComputeOptimized()
        {

            foreach (Product p in this.Seeds  )
            {
                GetTotalBudget ( p);
            }
            Seeds.Sort (new Comparison<Seed  >(compareProductBudgetAsc ));
            return Seeds[0];
        }
        private void  GetTotalBudget(Product p)
        {
            p.SelectPkgPrice=new List<PkgPrice>();
            int index=-1;
            int quantities=0;
            decimal totalamount=p.TotalAmount;
            while (totalamount >p.AllPkgPrice [0].PkgAmount )
            {
                index =binaryLocalize (p.AllPkgPrice,totalamount,p.AllPkgPrice.Count );
                if(index !=-1)
                {
                    quantities =(int)(totalamount /p.AllPkgPrice [index ].PkgAmount );
                    //quantities =(int)(totalamount %p.AllPkgPrice [index ].PkgAmount );
                    p.SelectPkgPrice.Add(new PkgPrice (){
                                             PkgID=p.AllPkgPrice[index].PkgID ,
                                             PkgAmount=p.AllPkgPrice[index].PkgAmount,
                                             Price=p.AllPkgPrice[index].Price ,
                                             Quantities=quantities
                                         });
                    p.Budget +=quantities *p.AllPkgPrice[index].Price ;
                }
                totalamount -=quantities *p.AllPkgPrice[index].PkgAmount;
            }
            if(totalamount !=0)
            {
                quantities =1;
                index =0;
                p.SelectPkgPrice.Add(new PkgPrice (){
                                             PkgID=p.AllPkgPrice[index].PkgID ,
                                             PkgAmount=p.AllPkgPrice[index].PkgAmount,
                                             Price=p.AllPkgPrice[index].Price ,
                                             Quantities=quantities
                                         });
                    p.Budget +=quantities *p.AllPkgPrice[index].Price ;
            }

        }
        /// <summary>
        /// 二分法搜索元素
        /// </summary>
        /// <param name="a"></param>
        /// <param name="x"></param>
        /// <param name="n"></param>
        /// <returns></returns>
        private int binarySearch(List<int >a,int x,int n)
        {
            int left=0;
            int right=n-1;
            while (left <=right)
            {
                int middle=(left +right )/2;
                if(x==a[middle])return middle;
                if(x>a[middle ])left =middle +1;
                else right =middle -1;
            }
            //没有找到
            return -1;
        }
        /// <summary>
        /// 二分法定位规格
        /// </summary>
        /// <param name="pkgPrices"></param>
        /// <param name="totalAmount"></param>
        /// <param name="n"></param>
        /// <returns></returns>
        private int binaryLocalize(List<PkgPrice > pkgPrices,decimal  totalAmount,int n)
        {
            if(totalAmount >=pkgPrices [n-1].PkgAmount )
                return n-1;

            int left=0;
            int right=n-1;
            while (left <=right )
            {
                int middle=(left+right )/2;
                if(totalAmount >=pkgPrices [middle ].PkgAmount &&totalAmount <pkgPrices [middle +1].PkgAmount )
                {
                    return middle ;
                }
                 if(totalAmount ==pkgPrices [middle +1].PkgAmount )
                {
                    return middle +1;
                }
                 if(totalAmount >pkgPrices [middle +1].PkgAmount )
                     left =middle +1;
                 else
                     right =middle -1;
            }
            return -1;
        }
        private int compareProductBudgetAsc(Product pro1,Product pro2)
        {
            if(pro1.Budget>pro2 .Budget )
                return 1;
            if(pro1.Budget<pro2 .Budget )
                return -1;
            else
                return 0;
        }

        private int comparePkgAmountAsc(PkgPrice pkg1,PkgPrice pkg2)
        {
            if(pkg1.PkgAmount >pkg2.PkgAmount )
                return 1;
            if(pkg1.PkgAmount <pkg2 .PkgAmount )
                return -1

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2010-03-24 02:51
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