最短路问题，尽管a!=b,可是同一条路測评数据会给你非常多个。因此在读入的时候要去最短的那条路存起来.........见了鬼了。坑爹

#include<iostream>
#include<vector>
#include<cstring>
#define maxn 205
#define inf 1<<30
using namespace std;
int n,m;
int vaule[maxn][maxn];
vector<int>mapp[maxn];
int visit[maxn];
int a,b;
int dijkstra()
{
	int d[maxn];
	fill(d,d+n,inf);
	fill(visit,visit+n,0);
	d[a]=0;
	while(!visit[b])
	{
		int v=-1;
		for(int i=0;i<n;i++)
		{
			if(!visit[i]&&(v==-1||d[i]<d[v])) v=i;
		}
		visit[v]=1;
		for(int i=0;i<mapp[v].size();i++)
		{
			int x=mapp[v][i];
			d[x]=min(d[x],vaule[v][x]+d[v]);
			//cout<<x<<"~"<<d[x]<<"~"<<endl;
		}
	}
	if(d[b]==inf) return -1;
	return d[b];
}
int main()
{
	while(cin>>n>>m)
	{
		for(int i=0;i<=n;i++) mapp[i].clear();
		memset(vaule,0,sizeof(vaule));
		for(int i=0;i<m;i++)
		{
			int x,y,z;
			cin>>x>>y>>z;
			if(x!=y&&!vaule[x][y])
			{
				mapp[x].push_back(y);
				mapp[y].push_back(x);
				vaule[x][y]=z;
				vaule[y][x]=z;
			}
			else 
			{
				vaule[x][y]=min(vaule[x][y],z);
				vaule[y][x]=min(vaule[y][x],z);
			}
		}
		cin>>a>>b;
		cout<<dijkstra()<<endl;
	}
	return 0;
}