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最新推荐文章于 2020-07-11 14:24:07 发布

原创最新推荐文章于 2020-07-11 14:24:07 发布 · 272 阅读

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#include <bits/stdc++.h>
//#include <ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;



#define pi acos(-1)
#define endl '\n'
#define me(x) memset(x,0,sizeof(x));
#define foreach(it,a) for(__typeof((a).begin()) it=(a).begin();it!=(a).end();it++)
typedef long long LL;
const int INF=0x3f3f3f3f;
const LL LINF=0x3f3f3f3f3f3f3f3fLL;
const int dx[]={-1,0,1,0,-1,-1,1,1};
const int dy[]={0,1,0,-1,1,-1,1,-1};
const int maxn=1e3+5;
const int maxx=2e6+100;
const double EPS=1e-7;
const int mod=1000000007;
template<class T>inline T min(T a,T b,T c) { return min(min(a,b),c);}
template<class T>inline T max(T a,T b,T c) { return max(max(a,b),c);}
template<class T>inline T min(T a,T b,T c,T d) { return min(min(a,b),min(c,d));}
template<class T>inline T max(T a,T b,T c,T d) { return max(max(a,b),max(c,d));}
//typedef tree<pt,null_type,less< pt >,rb_tree_tag,tree_order_statistics_node_update> rbtree;
/*lch[root] = build(L1,p-1,L2+1,L2+cnt);
    rch[root] = build(p+1,R1,L2+cnt+1,R2);中前*/
/*lch[root] = build(L1,p-1,L2,L2+cnt-1);
    rch[root] = build(p+1,R1,L2+cnt,R2-1);中后*/
long long gcd(long long a , long long b){if(b==0) return a;a%=b;return gcd(b,a);}


vector<pair<int,int> >E[maxn];
int n,m;
int d[maxn],inq[maxn];

void init()
{
    for(int i=0;i<maxn;i++)
    {
        E[i].clear();
        inq[i]=0;
        d[i]=INF;
    }
}
int main()
{
    while(cin>>n>>m)
    {
        init();
        for(int i=0;i<m;i++)
        {
            int x,y,z;
            cin>>x>>y>>z;
            E[x].push_back(make_pair(y,z));
            E[y].push_back(make_pair(x,z));
        }
        int s,t;
        cin>>s>>t;
        queue<int >Q;
        Q.push(s),d[s]=0,inq[s]=1;
        while(!Q.empty())
        {
            int now=Q.front();
            Q.pop();
            inq[now]=0;
            for(int i=0;i<E[now].size();i++)
            {
                int v=E[now][i].first;
                if(d[v]>d[now]+E[now][i].second)
                {
                    d[v]=d[now]+E[now][i].second;
                    if(inq[v]==1) continue;
                    inq[v]=1;
                    Q.push(v);
                }
            }
        }
        if(d[t]==INF) cout<<-1<<endl;
        else cout<<d[t]<<endl;
    }
}