6)图[5]最短路径

从单个顶点到其余各顶点之间的最短路径：

#include "iostream"
#include "vector"
#include "stack"
using namespace std;

const int MaxNumVertex  = 20; //最大顶点数
const int infinity = 65535;//无穷大
typedef int elementtype;       //elementtype 为int 型
class graph{
public:
    graph();
    ~graph();
    elementtype insertvertex(elementtype v); //在图中增加一个顶点
    elementtype insertedge(elementtype v,elementtype u,elementtype weight);//在图中增加一条从v顶点到u顶点的弧
    elementtype firstadj(elementtype v);//求图g中顶点v的第一个邻接点
    elementtype nextadj(elementtype v,elementtype m);//求图中顶点v的m邻接点之后的邻接点
    elementtype Dijkstra(elementtype v0);//求解从v0到各顶点的最短路径
    elementtype create();//创建图
    int  CurrentVertex;//当前顶点数

private:
    elementtype vertex[MaxNumVertex];//顶点表
    elementtype edge[MaxNumVertex][MaxNumVertex];//图中弧的类型
    
};

/*
*初始化
*/
graph::graph()
{
    CurrentVertex = 0; 
    int i,j;
    for (i=MaxNumVertex-1;i>=1;i--)
    {
        for (j=MaxNumVertex-1;j>=1;j--)
        {
            edge[i][j] = infinity;

        }
    }
    
}

/*
*在图中增加一个顶点
*/
elementtype graph::insertvertex(elementtype v)
{
    //判断这个顶点是否已经存在
    int i;
    bool flags = true;
    for(i=1; i<=CurrentVertex; i++)
    {
        if(vertex[i]==v)
        {
            flags = false;
            break;
        }
    }
    
    if(flags)
    {
        CurrentVertex++;
        vertex[CurrentVertex] = v;
    }else{
        cout<<v<<"顶点已经存在!"<<endl;
    }
    return 0;
}

/*
*在图中增加一条从v顶点到u顶点的弧
*/
elementtype graph::insertedge(elementtype v,elementtype u,elementtype weight)
{
    if(edge[v][u]!=infinity)
    {
        cout<<v<<"->"<<u<<"这条弧弧已经存在!"<<endl;
    }else{
        edge[v][u] = weight;
    }
    return 0;
}


/*
*求图中顶点v的第一个邻接点
*/
elementtype graph::firstadj(elementtype v)
{
    int u,i;
    bool flags = true;//用于判断是否存在邻接点
    for(i=1;i<=CurrentVertex;i++)
    {
        if(edge[v][i]!=0){
            u = i;
            flags = false;
            break;
        }
    }
    if(flags) u = 0;//邻接点不存在
    return u;
}

/*
*求图中顶点v的m邻接点以后的邻接点
*/
elementtype graph::nextadj(elementtype v,elementtype m)
{
    int i,u;
    bool flags = true;
    for(i=m+1;i<=CurrentVertex;i++)
    {
        if(edge[v][i]!=0)
        {
            u = i;
            flags = false;
            break;
        }
    }
    if(flags) u = 0;//邻接点不存在
    return u;
}

/*
*求解v0到各顶点的最短路径
*/
elementtype graph::Dijkstra(elementtype v0)
{
    int i,j,k,w,v;
    bool solved[20];
    int dist[20];
    vector<vector<int>>path(MaxNumVertex);//存储v0到各顶点的路径
    for(i=1;i<=CurrentVertex;i++)
    {
        solved[i] = false;
    }

    solved[v0] = true;//将v0设置为已解顶点
    for(i=1;i<=CurrentVertex;i++)
    {
        if(edge[v0][i]!=infinity)
        {
            dist[i] = edge[v0][i];
            path[i].push_back(v0);
            path[i].push_back(i);
        }else{
            dist[i] = infinity;
        }
    }

    for(i=1;i<CurrentVertex;i++)
    {
        int min = infinity;
        for(j=1;j<=CurrentVertex;j++)//在未解顶点中搜索最近的顶点v
        {
            if((solved[j]==false)&&(dist[j]<min))
            {
                min = dist[j];
                v = j;
            }
        }

        solved[v] = true;//所搜索到的当前最短的未解顶点为已解顶点
        for(w=firstadj(v);w!=0;w=nextadj(v,w))//修改v的后继路径以及长度
        {
            if(dist[v]+edge[v][w]<dist[w])
            {
                dist[w] = dist[v]+edge[v][w];//修改w的dist值
                path[w].clear();//清空w的path
                //重新形成w的path
                for(k=0;k<path[v].size();k++)
                {
                    path[w].push_back(path[v][k]);
                }
                path[w].push_back(w);
            }
        }
    }
    for(i=1;i<=CurrentVertex;i++)
    {
        if(v0!=i)
        {
            cout<<"dist["<<v0<<"->"<<i<<"]:"<<dist[i]<<endl;
            cout<<"path["<<v0<<"->"<<i<<"]:";
            for(j=0;j<path[i].size();j++)
            {
                if(j<path[i].size()-1)cout<<path[i][j]<<",";
                else cout<<path[i][j]<<endl;
            }
            cout<<endl;
        }
    }
    return 0;
}
/*
*创建图
*/
elementtype graph::create()
{
    int i,numv,v,u,weight;
    cout<<"please create graph"<<endl;
    cout<<"input numvertex(顶点数):";
    cin>>numv;
    cout<<"input vertex(顶点):";
    for(i=1;i<=numv;i++)
    {
        cin>>v;
        insertvertex(v);
    }
    cout<<"input num(u,v,weight)(弧的数目):";
    cin>>numv;
    for(i=1;i<=numv;i++)
    {
        cout<<"u->v,weight:";
        cin>>u>>v>>weight;
        insertedge(u,v,weight);
    }
    cout<<"graph create finish！"<<endl<<endl;
    return 0;
}
graph::~graph()
{
}

int main()
{
    graph g;
    g.create();
    int v0;
    cout<<"please input start(起点):";
    cin>>v0;
    g.Dijkstra(v0);
    return 0;
}