分支限界----最优装载

#include<iostream>
#include<bits/stdc++.h>
using namespace std;
int MaxLoading(int w[],int c,int n)
{
    queue<int>Q;
    int bestw=0;
    int i=1;
    int ew=0;
    int r=0;
    for(int j=2;j<=n;j++)
        r=r+w[j];
    Q.push(-1);
    while(true)
    {
        int wt=ew+w[i];
        if(wt<=c)
        {
            if(wt>bestw)
            {
                bestw=wt;
            }
            if(i<n)
                Q.push(wt);
        }
        if(ew+r>bestw&&i<n)
            Q.push(ew);
        ew=Q.front();
        Q.pop();
        if(ew==-1)
        {
            if(Q.empty())
                return bestw;
            Q.push(-1);
            ew=Q.front();
            Q.pop();
            i++;
            r=r-w[i];
        }
    }
}
int main()
{
    int w[100];
    int n,c;
    cout<<"输入物品的个数和船的载重量"<<endl;
    cin>>n>>c;
    cout<<"输入物品的质量"<<endl;
    for(int i=1; i<=n; i++)
        cin>>w[i];
    cout<<"最大质量为 "<<MaxLoading(w,c,n)<<endl;
    return 0;
}






#include <bits/stdc++.h>
using namespace std;
typedef struct QNode
{
    QNode *parent;
    int lchild;
    int weight;
} QNode;
int n;
int c;
int bestw;
int w[100];
int bestx[100];

//QNode *&bestE 的原因是 首先bestE是个地址， 其次引用为了赋值使用, 后边for循环中用到
void EnQueue(queue<QNode *> &q, int wt, int i, QNode *E, QNode *&bestE, int ch)
{
    if(i == n)
    {
        if(wt == bestw)
        {
            bestE = E;
            bestx[n] = ch;
            return;
        }
    }
    QNode *b=new QNode;
    b->weight = wt;
    b->lchild = ch;
    b->parent = E;
    q.push(b);
}
void MaxLoading()
{
    queue<QNode *>q;
    q.push(0);
    int i = 1;
    int Ew = 0, r = 0;
    bestw = 0;
    for(int j = 2; j <= n; ++j)
        r += w[j];
    QNode *E, *bestE; //bestE的作用是：结束while循环后，bestE指向最优解的叶子节点，然后通过bestE->parent找到装入了哪些物品。
    E = new QNode; //E这里作为一个中间量，连接parent和child
    E = 0;         //赋0是因为树的根的值是0，while刚开始的时候其代表root
    while(true)
    {
        int wt = Ew + w[i];
        if(wt <= c)
        {
            if(wt > bestw)
                bestw = wt;
            EnQueue(q, wt, i, E, bestE, 1);
        }
        if(Ew + r > bestw)
        {
            EnQueue(q, Ew, i, E, bestE, 0);
        }
        E = q.front();
        q.pop();
        if(E==0)
        {
            if(q.empty())
                break;
            q.push(0);
            E = q.front();
            q.pop();
            i++;
            r -= w[i];
        }
        Ew = E->weight; //不要忘记更新最新节点的值
    }
    for(int j = n - 1; j > 0; j--)
    {
        bestx[j] = bestE->lchild;
        bestE = bestE->parent;
    }
}

int main()
{
    cout<<"输入物品的个数和船的载重量"<<endl;
    cin>>n>>c;
    cout<<"输入物品的质量"<<endl;
    for(int i=1; i<=n; i++)
        cin>>w[i];
    MaxLoading();
    cout<<"最大质量为 "<<bestw<<endl;
    cout<<"装载的物品为 \n";
    for(int i = 1; i <= n; ++i)
        cout<<bestx[i]<<" ";
    cout<<endl;

    /*for(int i = 1; i <= n; ++i)
        if(bestx[i] == 1)
          printf("%d ", i);*/
    return 0;
}










#include<iostream>
#include<bits/stdc++.h>
using namespace std;
#define inf 0x3f3f3f
/*bool operator < (const int &a,const int &b) const
{
    return a<b;
}*/
queue<int>Q;
void EnQueue(int wt,int bestw,int i,int n)
{
    if(i==n)
    {
        if(wt>bestw)
        {
            bestw=wt;
        }
    }
    else
        Q.push(wt);

}
int MaxLoading(int w[],int c,int n)
{
    int i=1;
    int ew=0;
    int bestw=0;
    Q.push(ew);
    Q.push(-1);
    while(true)
    {
        if(ew+w[i]<=c)
        {
            EnQueue(ew+w[i],bestw,i,n);
            EnQueue(ew,bestw,i,n);
            Q.pop();
            ew=Q.front();
            if(ew==-1)
            {
                Q.pop();
                if(Q.empty())
                    return bestw;
                Q.push(-1);
                ew=Q.front();
                i++;
            }
        }
    }
}

int main()
{
    int w[100];
    int n,c;
    cout<<"输入物品的个数和船的载重量"<<endl;
    cin>>n>>c;
    cout<<"输入物品的质量"<<endl;
    for(int i=1;i<=n;i++)
        cin>>w[i];
    cout<<"最大质量为 "<<MaxLoading(w,c,n)<<endl;
    return 0;
}




#include<iostream>
#include<bits/stdc++.h>
using namespace std;
#define inf 0x3f3f3f
/*bool operator < (const int &a,const int &b) const
{
    return a<b;
}*/
void EnQueue(queue<int>&Q,int wt,int bestw,int i,int n)
{
    if(i==n)
    {
        if(wt>bestw)
        {
            bestw=wt;
        }
    }
    else
        Q.push(wt);

}int bestw;
int MaxLoading(queue<int>&Q,int w[],int c,int n)
{
    int i=1;
    int ew=0;
    int r=0;
    for(int j=2;j<=n;j++)
        r=r+w[j];
    //Q.push(ew);
    Q.push(-1);
    while(true)
    {
        if(ew+w[i]<=c)
        {
            EnQueue(Q,ew+w[i],bestw,i,n);
        }
        EnQueue(Q,ew,bestw,i,n);
        //Q.pop();
        ew=Q.front();
        Q.pop();
        if(ew==-1)
        {
            //Q.pop();
            if(Q.empty())
                return bestw;
            Q.push(-1);
            ew=Q.front();
            Q.pop();
            i++;
        }
    }
}


int main()
{
    bestw=0;
    queue<int>Q;
    int w[100];
    int n,c;
    cout<<"输入物品的个数和船的载重量"<<endl;
    cin>>n>>c;
    cout<<"输入物品的质量"<<endl;
    for(int i=1; i<=n; i++)
        cin>>w[i];
    cout<<"最大质量为 "<<MaxLoading(Q,w,c,n)<<endl;
    return 0;
}

来源：CSDN

作者：啦啦啦mmm

链接：https://blog.csdn.net/qq_45593796/article/details/103764655