算法-动态规划法解决背包问题

https://blog.csdn.net/qq_40788630/article/details/79503946

动态规划解决0/1背包问题的C#代码，迭代，下面的代码还没有使用动态规划

     class Program
{
    static void Main(string[] args)
    {
        Program p = new Program();
        Result a = p.maxValue(p.buildItem(), 150);
        foreach (Item i in a.items)
        {
            Console.WriteLine(i);
        }

        Console.WriteLine(a.value);

        Console.ReadKey();
    }

    List buildItem()
    {
        string[] names = { "AA", "B" };
        int[] vals = { 50, 30};
        int[] weights = { 130, 40 };
        List items = new List();
        for (int i = 0; i < names.Length; i++)
        {
            items.Add(new Item(names[i], vals[i], weights[i]));
        }
        return items;
    }

    //oraSet 备选的物品箱 leftRoom剩余的空间大小
    Result maxValue(List oraSet, int leftRoom)
    {
        if (oraSet.Count == 0 || leftRoom == 0)//退出条件，备选箱没东西了或者背包满了
        {
            return new Result(0, new List());
        }
        else if (oraSet[0].getWeight() > leftRoom)//如果物品体积太大，直接丢弃
        {
            List a = new List();
            for (int i = 1; i < oraSet.Count; i++)
            {
                a.Add(oraSet[i]);
            }

            return maxValue(a, leftRoom);
        }
        else
        {
            Item nextItem = oraSet[0];//取出第一个
            List a = new List();
            for (int i = 1; i < oraSet.Count; i++)
            {
                a.Add(oraSet[i]);
            }
            Result l = maxValue(a, leftRoom - (int)nextItem.getWeight());//把箱子剩下，把剩余空间装满的结果返回。注意，传入的参数：是剩下的物品
            int left = l.value + nextItem.getValue();//如果要这个物品，得到总价值

            Result r = maxValue(a, leftRoom);//如果丢弃此物品，得到的总价值.注意，传入的参数：是剩下的物品
            if (left > r.value)//根据价值大小选择要哪些物品
            {
                l.items.Add(nextItem);//说明还要此物品，把此物品返回
                return new Result(left, l.items);//结果包含此物品
            }
            else
            {
                return new Result(r.value, r.items);//丢弃此物品，把结果返回
            }
        }
    }
}

public class Result
{
    public int value;
    public List items = new List();

    public Result(int v, List its)
    {
        this.value = v;
        this.items = its;
    }
}

public class Item
{
    string name;
    int value;
    int weight;
    public Item(string n, int v, int w)
    {
        this.name = n;
        this.value = v;
        this.weight = w;
    }

    public string getName()
    {
        return this.name;
    }

    public int getValue()
    {
        return this.value;
    }

    public int getWeight()
    {
        return this.weight;
    }

    public override string ToString()
    {
        string result = " < " + this.name + " , " + this.value + " , " + this.weight + ">";
        return result;
    }
}