/*dijkstra*/
#include<cstdio>
#include<algorithm>
#define MAX 0x3f3f3f
using namespace std;
int dis[211],vis[211];
int len[211][211];
int n,m,s,t;
int min(int x,int y)
{
      if(x >= y)
            return y;
      return x;      
}
void dijkstra()
{
      int i,j,k;
      for( i = 0; i < n; i++)
      {
            dis[i] = MAX;
            vis[i] = 0;
      }            
      dis[s] = 0;
      while(1)
      {
            k = -1;
            for( i = 0; i < n ; i++)
            if(!vis[i] && (k==-1 ||dis[i] < dis[k]))
            k = i;
            if(k == -1)  break;
            vis[k] = 1;
            for(i = 0; i < n; i++)
            dis[i] = min( dis[i], dis[k]+len[i][k]);
      }
      if(dis[t] == MAX)
            printf("-1\n");
      else      
            printf("%d\n",dis[t]);
}
int main()
{
      int i,j,k,a,b,x;
      while(scanf("%d%d",&n,&m)!=EOF)
      {
            for( i = 0; i < n; i++)
            for( j = 0; j < n; j++)
            len[i][j] = MAX;
            while(m--)
            {
                  scanf("%d%d%d",&a,&b,&x);
                  if(len[a][b] > x)
                  {
                        len[a][b] = x;
                        len[b][a] = x;
                  }      
            }
            scanf("%d%d",&s, &t);
            dijkstra();
      }
      return 0;
}

/*spfa*/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<queue>
#include<vector>
#define INF 0x3f3f3f
#include<algorithm>
using namespace std;
int n,m;
int head[2100],edgenum,dis[2100];
bool vis[2100];
struct node{
      int start,end,len,next;
}p[20010];
void add(int u,int v,int w)
{
      node E = {u,v,w,head[u]};
      p[edgenum] = E;
      head[u] = edgenum++;
}
void spfa(int s,int t)
{
      memset(vis,0,sizeof(vis));
      memset(dis,0x3f,sizeof(dis));
      queue<int> q;
      q.push(s);
      dis[s] = 0;
      vis[s] = 1;
      while(!q.empty())
      {
            int u = q.front(); 
            q.pop();
            vis[u] = 0;
            for(int i = head[u]; i!=-1;i=p[i].next)
            {
                  int v = p[i].end;
                  if(dis[v]>dis[u]+p[i].len)
                  {
                        dis[v]=dis[u]+p[i].len;
                        if(!vis[v])
                        {
                              vis[v] =1;
                              q.push(v);
                        }
                  }
            }
      }
      if(dis[t]>10000)
            printf("-1\n");
      else      
            printf("%d\n",dis[t]);                  
}
int main()
{
      int i,j,k;
      while(scanf("%d%d",&n,&m)!=EOF)
      {
            memset(head,-1,sizeof(head));
            edgenum = 0;
            int a,b,c;
            while(m--)
            {
                  scanf("%d%d%d",&a,&b,&c);
                  add(a,b,c);
                  add(b,a,c);
            }
            int s1,e1;
            scanf("%d%d",&s1,&e1);
            spfa(s1,e1);
      }
      return 0;
}

/*floyd*/
#include<stdio.h>
#include<string.h>
#define min(a,b) a>b?b:a
#define INF 0x3f3f3f3f
int n,m;
int dis[211][211];
void floyd()
{
	int i,j,k;
	for(k = 0; k < n; k++)
	for(i = 0; i < n; i++)
	for(j = 0; j < n; j++) 	
	dis[i][j] = min( dis[i][j], dis[i][k]+dis[k][j] );
}
int main()
{
	int i,j,k;
	while(scanf("%d%d",&n,&m)!=EOF)
	{
		int a,b,x;
		for(i = 0;i < n; i++)
		{
			for(j = 0; j < n; j++)
			if(i==j)
			dis[i][j] = 0;
			else
			dis[i][j] = INF;
		}
		while(m--)
		{
			scanf("%d%d%d",&a,&b,&x);
			if(dis[a][b] > x)
			dis[a][b] = dis[b][a] =x;
		}
		int from,to;
		scanf("%d%d",&from,&to);
		floyd();
		if(dis[from][to]==INF)
		printf("-1\n");
		else
		printf("%d\n",dis[from][to]);
	}
	return 0; 
} 

版权声明：原创文章，若要转载，请与博主联系，谢谢