dijsktra(邻接表实现，贪心算法)

# include<iostream>
# include<cstring>
# define inf 0x3f3f3f3f
# define nil -1
using namespace std;
const int maxn=100+5;
typedef struct arcnode{
	int adjnode;
	int weight;
	arcnode *nextarc;
}arcnode;
typedef struct vnode{   
   int data; 
	arcnode *firstarc;
}vnode;
typedef struct graph{
	vnode vertexs[maxn];
	int vertexnum;  //顶点数目 
	int edgenum;   //边数目 
}graph;
int pre[maxn];
int dis[maxn];
int vis[maxn]; 
int find(graph g,int v)
{
	for(int i=0;i<g.vertexnum;i++)
	 {
	 	if(g.vertexs[i].data==v)
	 	  return i;
	 }
	
}
void init(graph &g)
{
	cin>>g.vertexnum>>g.edgenum;
	for(int i=0;i<g.vertexnum;i++)
	{
		cin>>g.vertexs[i].data;
		g.vertexs[i].firstarc=NULL;
	}
	 int u,v,w;
	for(int i=0;i<g.edgenum;i++)
	{
		cin>>u>>v>>w;
		arcnode *s=new arcnode();
		int index_u=find(g,u);
		int index_v=find(g,v);
		s->adjnode=index_v;
		s->weight=w;
		s->nextarc=g.vertexs[index_u].firstarc;
		 g.vertexs[index_u].firstarc=s;
	}
	
}
void relax(int u,int v,int w)
{
	if(dis[v]>dis[u]+w)
	{
		dis[v]=dis[u]+w;
		pre[v]=u;
	}
}
void init_signal_source(graph g,int s)
{
	for(int i=0;i<g.vertexnum;i++)
	{
		pre[i]=nil;
		dis[i]=inf;
	}
	dis[s]=0;    //源点距离初始化为0 
}
void printpath(graph g,int s,int v)
{
	if(v==s)
	{
		cout<<g.vertexs[s].data;
	}
	else if(pre[v]==nil)
	      {
	      	cout<<"no path from "<<g.vertexs[s].data <<"to "<<g.vertexs[v].data;
		  }
		  else {
		  	   printpath(g,s,pre[v]);
		  	   cout<<"->"<<g.vertexs[v].data;
		  }
	
	
}
void dijsktra(graph g,int s)
{
	init_signal_source(g,s);
	for(int j=1;j<g.vertexnum;j++)//其余g.vertexnum-1顶点 
	{
		int min_dis=inf;
		int min_index;	
		for(int i=0;i<g.vertexnum;i++)  //抽取最小距离索引 
		{
			if(!vis[i]&&dis[i]<min_dis)
			{
				min_dis=dis[i];
				min_index=i;
			}
		}
		vis[min_index]=1;//加入集合 
	 	arcnode *w=g.vertexs[min_index].firstarc;
	  	while(w)
	  	{
	  	relax(min_index,w->adjnode,w->weight);
	  	w=w->nextarc;
		  }
	}
	
}
int main()
{
	graph g;
	init(g);
	int  v;
	cin>>v;
	int index_v=find(g,v);
	memset(vis,0,sizeof(vis));
     dijsktra(g,index_v);
	for(int i=0;i<g.vertexnum;i++)
	 {
	 	if(i!=index_v)
	 	{ 
	 	  printpath(g,index_v,i);
	 	 if(dis[i]!=inf)
	 	    cout<<" "<<dis[i]<<endl;
	 	else cout<<"正无穷"<<endl;
	     }
	  }   
	
	return 0;
}